# The LearningOnline Network with CAPA
#
# $Id: lonproblemanalysis.pm,v 1.134 2008/12/12 07:26:28 raeburn Exp $
#
# Copyright Michigan State University Board of Trustees
#
# This file is part of the LearningOnline Network with CAPA (LON-CAPA).
#
# LON-CAPA is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# LON-CAPA is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with LON-CAPA; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#
# /home/httpd/html/adm/gpl.txt
#
# http://www.lon-capa.org/
#
package Apache::lonproblemanalysis;

use strict;
use Apache::lonnet;
use Apache::loncommon();
use Apache::lonhtmlcommon();
use Apache::loncoursedata();
use Apache::lonstatistics;
use Apache::lonlocal;
use Apache::lonstathelpers();
use Apache::lonstudentsubmissions();
use HTML::Entities();
use Time::Local();
use capa;
use lib '/home/httpd/lib/perl/';
use LONCAPA;
  

my $plotcolors = ['#33ff00', 
                  '#0033cc', '#990000', '#aaaa66', '#663399', '#ff9933',
                  '#66ccff', '#ff9999', '#cccc33', '#660000', '#33cc66',
                  ]; 

my @SubmitButtons = ({ name => 'PrevProblemAnalysis',
                       text => 'Previous Problem' },
                     { name => 'ProblemAnalysis',
                       text => 'Analyze Problem Again' },
                     { name => 'NextProblemAnalysis',
                       text => 'Next Problem' },
                     { name => 'break'},
                     { name => 'SelectAnother',
                       text => 'Choose a different Problem' });

sub BuildProblemAnalysisPage {
    my ($r,$c)=@_;
    #
    my %Saveable_Parameters = ('Status' => 'scalar',
                               'Section' => 'array',
                               'Groups' => 'array',
                               'NumPlots' => 'scalar',
                               'AnalyzeOver' => 'scalar',
                               );
    &Apache::loncommon::store_course_settings('problem_analysis',
                                              \%Saveable_Parameters);
    &Apache::loncommon::restore_course_settings('problem_analysis',
                                                \%Saveable_Parameters);
    #
    &Apache::lonstatistics::PrepareClasslist();
    #
    $r->print(&CreateInterface());
    #
    my @Students = @Apache::lonstatistics::Students;
    #
    if (@Students < 1 && exists($env{'form.firstrun'})) {
        $r->print('<div class="LC_warning">'
                 .&mt('There are no students in the sections/groups selected.')
                 .'</div>'
        );
    }
    #
    my @CacheButtonHTML = 
        &Apache::lonstathelpers::manage_caches($r,'Statistics','stats_status');
    $r->rflush();
    #
    my $problem_types = '(option|radiobutton|numerical)';
    if (exists($env{'form.problemchoice'}) && 
        ! exists($env{'form.SelectAnother'})) {
        foreach my $button (@SubmitButtons) {
            if ($button->{'name'} eq 'break') {
                $r->print("<br />\n");
            } else {
                $r->print('<input type="submit" name="'.$button->{'name'}.'" '.
                          'value="'.&mt($button->{'text'}).'" />');
                $r->print('&nbsp;'x5);
            }
        }
        foreach my $html (@CacheButtonHTML) {
            $r->print($html.('&nbsp;'x5));
        }
        #

        # This is commented out pending actual implementation of 
        # CSV and Excel output.
        #$r->print(&Apache::lonstathelpers::submission_report_form
        #                                              ('problem_analysis'));
        #
        $r->print('<hr />');
        $r->rflush();
        #
        # Determine which problem we are to analyze
        my $current_problem = &Apache::lonstathelpers::get_target_from_id
            ($env{'form.problemchoice'});
        #
        my ($navmap,$prev,$curr,$next) = 
            &Apache::lonstathelpers::get_prev_curr_next($current_problem,
                                                        $problem_types,
                                                        'response',
                                                        );
        if (exists($env{'form.PrevProblemAnalysis'}) && defined($prev)) {
            $current_problem = $prev;
        } elsif (exists($env{'form.NextProblemAnalysis'}) && defined($next)) {
            $current_problem = $next;
        } else {
            $current_problem = $curr;
        }
        #
        # Store the current problem choice and send it out in the form
        $env{'form.problemchoice'} = 
            &Apache::lonstathelpers::make_target_id($current_problem);
        $r->print('<input type="hidden" name="problemchoice" value="'.
                  $env{'form.problemchoice'}.'" />');
        #
        if (! defined($current_problem->{'resource'})) {
            $r->print('resource is undefined');
        } else {
            my $resource = $current_problem->{'resource'};
            $r->print('<h1>'.$resource->compTitle.'</h1>');
            $r->print('<h3>'.$resource->src.'</h3>');
            $r->print('<h4>'.&Apache::lonstatistics::section_and_enrollment_description().'</h4>');
            if ($env{'form.show_prob'} eq 'true') {
                $r->print('<hr />'
                         .&Apache::lonstathelpers::render_resource($resource)
                         .'<hr />'
                );
            }
            $r->rflush();
	    if (@Students) {
		my %Data = &Apache::lonstathelpers::get_problem_data
		    ($resource->src);
		my $problem_data = $Data{$current_problem->{'part'}.
					     '.'.
					     $current_problem->{'respid'}};
		if ($current_problem->{'resptype'} eq 'option') {
		    &OptionResponseAnalysis($r,$current_problem,
					    $problem_data,
					    \@Students);
		} elsif ($current_problem->{'resptype'} eq 'radiobutton') {
		    &radio_response_analysis($r,$current_problem,
					     $problem_data,
					     \@Students);
		} elsif ($current_problem->{'resptype'} eq 'numerical') {
		    &numerical_response_analysis($r,$current_problem,
						 $problem_data,\@Students);
		} else {
		    $r->print('<div class="LC_warning">'
                             .&mt('Analysis of [_1] is not supported.'
                                 ,$current_problem->{'resptype'})
                             .'</div>'
                    );
		}
	    }
        }
        $r->print('<hr />');
    } else {
        my $submit_button = '<input type="submit" '.
            'name="ProblemAnalysis" value="'.
            &mt('Analyze Problem').'" />';
        $r->print($submit_button);
        $r->print('&nbsp;'x5);
        $r->print('<h3>'.&mt('Please select a problem to analyze').'</h3>');
        $r->print(&Apache::lonstathelpers::problem_selector($problem_types,
                                                            $submit_button));
    }
}

#########################################################
#########################################################
##
##      Numerical Response Routines
##
#########################################################
#########################################################
sub numerical_response_analysis {
    my ($r,$problem,$problem_analysis,$students) = @_;
    my $c = $r->connection();
    #
    if ($env{'form.AnalyzeOver'} !~ /^(tries|time)$/) {
        $r->print('Bad request');
    }
    #
    my ($resource,$partid,$respid) = ($problem->{'resource'},
                                      $problem->{'part'},
                                      $problem->{'respid'});
    # Gather student data
    my $response_data = &Apache::loncoursedata::get_response_data
        ([&Apache::lonstatistics::get_selected_sections()],
         [&Apache::lonstatistics::get_selected_groups()],
         $Apache::lonstatistics::enrollment_status,
         $resource->symb,$respid);
    #
    $problem_analysis->{'answercomputed'} = 1;
    if ($problem_analysis->{'answercomputed'}) {
        my $answers = 
            &Apache::lonstathelpers::GetStudentAnswers($r,$problem,$students,
                                                       'Statistics',
                                                       'stats_status');
        $r->print(&numerical_one_dimensional_plot($r,600,150,$answers));
    }
    #
    if (ref($response_data) ne 'ARRAY') {
        $r->print('<div class="LC_warning">'
                 .&mt('There is no submission data for this resource.')
                 .'</div>'
        );
        return;
    }
    my $analysis_html = '<table>';
    for (my $plot_num = 1;$plot_num<=$env{'form.NumPlots'};$plot_num++) {
        my $restriction_function;
        my $header_message;
        my $stats_message;
        my $post_message; # passed through &mt sooner rather than later
        my $no_data_message;
        my @extra_data;
        if ($env{'form.AnalyzeOver'} eq 'tries') {
            $restriction_function = sub {($_[0]->{'tries'} == $plot_num?1:0)};
            $header_message = 'Attempt [_1]';
            $stats_message = 
                '[_1] submissions, [_2] correct, [_3] incorrect';
            $post_message = '';
            $no_data_message = 'No data exists for attempt [_1].';
        } else {
            my $starttime = &Apache::lonhtmlcommon::get_date_from_form
                ('startdate_'.$plot_num);
            my $endtime = &Apache::lonhtmlcommon::get_date_from_form
                ('enddate_'.$plot_num);
            ($starttime,$endtime) = &ensure_start_end_times
                ($starttime,$endtime,
                 &get_time_from_row($response_data->[0]),
                 &get_time_from_row($response_data->[-1]),
                 $plot_num);
            $header_message = 'Data from [_2] to [_3]';
            $extra_data[0] = &Apache::lonlocal::locallocaltime($starttime);
            $extra_data[1] = &Apache::lonlocal::locallocaltime($endtime);
            #
            $stats_message = 
                '[_1] submissions from [_4] students, [_2] correct, [_3] incorrect';
            #
            $post_message = 
                &mt('Start time: [_1]',
                    &Apache::lonhtmlcommon::date_setter
                    ('Statistics','startdate_'.$plot_num,$starttime)).
                '<br />'.
                &mt('End time: [_1]',
                    &Apache::lonhtmlcommon::date_setter
                    ('Statistics','enddate_'.$plot_num,$endtime));
            $restriction_function = 
                sub { 
                    my $t = $_[0]->{'timestamp'};
                    if ($t >= $starttime && $t < $endtime) {
                        return 1;
                    } else { 
                        return 0;
                    }
                };
            $no_data_message = 'No data for [_2] to [_3]';
        }
        #
        my ($correct,$answers) = 
            &numerical_determine_answers($r,$resource,$partid,
                                         $respid,$students);
        if ($c->aborted()) { return; };
        #
        my ($responses,$stats) = 
            &numerical_classify_responses($response_data,$correct,
                                          $restriction_function);
        if ($stats->{'submission_count'} == 0) {
            $analysis_html.= 
                '<tr><td colspan="2"><div class="LC_warning">'.
                &mt($no_data_message,$plot_num,@extra_data).
                '</div></td></tr>';
        } else {
            $analysis_html.= 
                '<tr><td colspan="2" align="center"><font size="+1"><b>'.
                &mt($header_message,$plot_num,@extra_data).
                '</b></font></td></tr>'.
                '<tr><td colspan="2" align="center">'.
                &mt($stats_message,
                    $stats->{'submission_count'},
                    $stats->{'correct_count'},
                    $stats->{'incorrect_count'},
                    $stats->{'students'},
                    @extra_data).
                    '</td></tr>'.
                    '<tr>'.'<td valign="top" align="center">'.
                    &numerical_plot_percent($r,$responses,$stats).'</td>'.
                    '<td align="center" valign="top">'.
                    &numerical_plot_differences($r,$responses,$stats).'</td>'.
                    '</tr>';
        }
        if ($post_message ne '') {
            $analysis_html .=
                '<tr><td colspan="2">'.$post_message.'</td></tr>';
        }
    }
    $analysis_html.='</table>';
    $r->print($analysis_html);
    #
    return;
}

sub numerical_plot_percent {
    my ($r,$responses,$stats) = @_;
    #
    my $total = $stats->{'submission_count'};
    return '' if ($total == 0);
    my $max_bins = 50;
    my $lowest_percent = $stats->{'min_percent'};
    my $highest_percent = $stats->{'max_percent'};
    my $percent_spread = $highest_percent - $lowest_percent;
    foreach (qw/20 30 40 50 100 200/) {
        if ($percent_spread < $_) {
            $highest_percent =$_/2;
            last;
        }
    }
    $percent_spread = $highest_percent - $lowest_percent;
    my $bin_size = 1;
    foreach (qw/0.01 0.05 0.1 0.5 1 2 5 10 20 25 50 100/) {
        if ($lowest_percent/2 < $_){
            $bin_size = $_;
	    if ( ($percent_spread/$bin_size) < $max_bins ) {
		last;
	    }
        }
    }
    my @bins;
    for (my $bin = -$highest_percent;$bin<0;$bin+=$bin_size) {
        push (@bins,$bin);
    }
    for (my $bin = 0; $bin<$highest_percent;$bin+=$bin_size) {
        push (@bins,$bin);
    }
    push(@bins,$highest_percent);
    #
    my @correct;
    my @incorrect;
    my @count;
    while (my ($ans,$submissions) = each(%$responses)) {
        while (my ($submission,$counts) = each(%$submissions)) {
            my ($correct_count,$incorrect_count) = @$counts;
	    my $scaled_value = 
		($ans) ? 100*($submission-$ans)/abs($ans)
		       : 0;
            if ($scaled_value < $bins[0]) {
                $bins[0]=$scaled_value -1;
            }
            my $bin;
            for ($bin=0;$bin<$#bins;$bin++) {
                last if ($bins[$bin]>$scaled_value);
            }
            $correct[$bin-1]+=$correct_count;
            $incorrect[$bin-1]+=$incorrect_count;
            $count[$bin-1]+=$correct_count+$incorrect_count;
        }
    }
    #
    my @plot_correct   = @correct;
    my @plot_incorrect = @incorrect;
    my $max;
    for (my $i=0;$i<$#bins;$i++) {
        $plot_correct[$i]   *= 100/$total;
        $plot_incorrect[$i] *= 100/$total;
        if (! defined($max) || 
            $max < $plot_correct[$i]+$plot_incorrect[$i] ) {
            $max = $plot_correct[$i]+$plot_incorrect[$i];
        }
    }
    foreach (qw/1 5 10 15 20 25 30 40 50 75 100/) {
        if ($max <$_) { $max = $_; last; }
    }
    #
    my $title = &mt('Percent Difference');
    my @labels = (1..scalar(@bins)-1);
    my $graph = &Apache::loncommon::DrawBarGraph
        ($title,'Percent Difference from Correct','Percent of Answers',
         $max,['#33FF00','#FF3300'],\@labels,\@plot_correct,\@plot_incorrect,
         {xskip=>1});
    #
    my $table = $graph.$/.
        &numerical_bin_table(\@bins,\@labels,\@incorrect,\@correct,\@count).$/;
    return $table;
}

sub numerical_plot_differences {
    my ($r,$responses,$stats) = @_;
    #
    my $total = $stats->{'submission_count'};
    return '' if ($total == 0);
    my $max_bins = 21;
    my $min_bin_size = $stats->{'min_abs'};
    my $low_bin  = $stats->{'lowest_ans'}-$stats->{'max_bin_size'};
    my $high_bin = $stats->{'highest_ans'}+$stats->{'max_bin_size'};
    if ($high_bin > 0 && $low_bin > -$high_bin) {
        $low_bin = -$high_bin;
    } elsif ($low_bin < 0 && $high_bin < -$low_bin) {
        $high_bin = -$low_bin;
    }
    if ($high_bin == $low_bin) {
	$high_bin+=1;
	$low_bin-=1;
    }
    if (!$min_bin_size ||
        ($high_bin -$low_bin)/$min_bin_size * 2 > $max_bins) {
        $min_bin_size = abs($high_bin - $low_bin) / $max_bins * 2;
    }
    my @bins;
    for (my $num = $low_bin;$num <= $high_bin;$num+=($min_bin_size/2)) {
        push(@bins,$num);
    }
    #
    my @correct;
    my @incorrect;
    my @count;
    while (my ($ans,$submissions) = each(%$responses)) {
        while (my ($submission,$counts) = each(%$submissions)) {
            my ($correct_count,$incorrect_count) = @$counts;
            my $scaled_value = $submission-$ans;
            if ($scaled_value < $bins[0]) {
                $bins[0]=$scaled_value-1;
            }
            my $bin=0;
            for ($bin=0;$bin<$#bins;$bin++) {
                last if ($bins[$bin]>$scaled_value);
            }
            $correct[$bin-1]+=$correct_count;
            $incorrect[$bin-1]+=$incorrect_count;
            $count[$bin-1]+=$correct_count+$incorrect_count;
        }
    }
    my @plot_correct   = @correct;
    my @plot_incorrect = @incorrect;
    my $max;
    for (my $i=0;$i<=$#bins;$i++) {
        $plot_correct[$i]   *= 100/$total;
        $plot_incorrect[$i] *= 100/$total;
        if (! defined($max) || 
            $max < $plot_correct[$i]+$plot_incorrect[$i] ) {
            $max = $plot_correct[$i]+$plot_incorrect[$i];
        }
    }
    foreach (qw/1 5 10 15 20 25 30 40 50 75 100/) {
        if ($max <$_) { $max = $_; last; }
    }
    #
    my $title = &mt('Difference between submission and correct');
    my @labels = (1..scalar(@bins)-1);
    my $graph = &Apache::loncommon::DrawBarGraph
        ($title,'Difference from Correct','Percent of Answers',
         $max,['#33FF00','#FF3300'],\@labels,\@plot_correct,\@plot_incorrect,
         {xskip=>1});
    #
    my $table = $graph.$/.
        &numerical_bin_table(\@bins,\@labels,\@incorrect,\@correct,\@count).$/;
    return $table;
}

sub numerical_classify_responses {
    my ($full_row_data,$correct,$function) = @_;
    my %submission_data;
    my %students;
    my %stats;
    my $max=0;
    foreach my $row (@$full_row_data) {
        my %subm = &hashify_attempt($row);
        if (ref($correct) eq 'HASH') {
            my $s_correct = $correct->{$subm{'student'}};
            $subm{'correct'} = $s_correct->{'answer'};
            foreach my $item ('unit','ans_low','ans_high') {
                $subm{$item} = $s_correct->{$item};
            }
        } else { # This probably never happens....
            $subm{'correct'} = $correct->{'answer'};
            $subm{'unit'} = $correct->{'unit'};
        }
        # 
        my $abs_low =abs($subm{'correct'}-$subm{'ans_low'});
        my $abs_high=abs($subm{'correct'}-$subm{'ans_high'});
        if (! defined($stats{'min_abs'}) ||
            $stats{'min_abs'} > $abs_low) {
            $stats{'min_abs'} = $abs_low;
        }
        if ($stats{'min_abs'} > $abs_high) {
            $stats{'min_abs'} = $abs_high;
        }
        if (! defined($stats{'max_abs'}) ||
            $stats{'max_abs'} < $abs_low) {
            $stats{'max_abs'} = $abs_low;
        }
        if ($stats{'max_abs'} < $abs_high) {
            $stats{'max_abs'} = $abs_high;
        }
        my $low_percent;
        my $high_percent;
        if (defined($subm{'correct'}) && $subm{'correct'} != 0) {
            $low_percent  = 100 * abs($abs_low  / $subm{'correct'});
            $high_percent = 100 * abs($abs_high / $subm{'correct'});
        }
        if (! defined($stats{'min_percent'}) ||
            $stats{'min_percent'} > $low_percent) {
            $stats{'min_percent'} = $low_percent;
        }
        if ($stats{'min_percent'} > $high_percent) {
            $stats{'min_percent'} = $high_percent;
        }
        if (! defined($stats{'max_percent'}) ||
            $stats{'max_percent'} < $low_percent) {
            $stats{'max_percent'} = $low_percent;
        }
        if ($stats{'max_percent'} < $high_percent) {
            $stats{'max_percent'} = $high_percent;
        }
        if (! defined($stats{'lowest_ans'}) ||
            $stats{'lowest_ans'} > $subm{'correct'}) {
            $stats{'lowest_ans'} = $subm{'correct'};
        }
        if (! defined($stats{'highest_ans'}) ||
            $stats{'highest_ans'} < $subm{'correct'}) {
            $stats{'highest_ans'} = $subm{'correct'};
        }
        # 
        $subm{'submission'} =~ s/=\d+\s*$//;
        if (&$function(\%subm)) {
            my $scaled = '1';
            my ($sname,$sdom) = split(':',$subm{'student'});
            my ($myunit,$mysub) = ($subm{'unit'},$subm{'submission'});
            my $result = 
                &capa::caparesponse_get_real_response($myunit,
                                                      $mysub,
                                                      \$scaled);
#            &Apache::lonnet::logthis('scaled = '.$scaled.' result ='.$result);
            next if (! defined($scaled));
#            next if ($result ne '6');
            my $submission = $scaled;
            $students{$subm{'student'}}++;
            $stats{'submission_count'}++;
            if (&numerical_submission_is_correct($subm{'award'})) { 
                $stats{'correct_count'}++;
                $submission_data{$subm{'correct'}}->{$submission}->[0]++;
            } elsif (&numerical_submission_is_incorrect($subm{'award'})) { 
                $stats{'incorrect_count'}++;
                $submission_data{$subm{'correct'}}->{$submission}->[1]++;
            }
        }
    }
    $stats{'correct_count'} |= 0;
    $stats{'incorrect_count'} |= 0;
    $stats{'students'}=scalar(keys(%students));
    return (\%submission_data,\%stats);
}

sub numerical_submission_is_correct {
    my ($award) = @_;
    if ($award =~ /^(APPROX_ANS|EXACT_ANS)$/) {
        return 1;
    } else {
        return 0;
    }
}

sub numerical_submission_is_incorrect {
    my ($award) = @_;
    if ($award =~ /^(INCORRECT)$/) {
        return 1;
    } else {
        return 0;
    }
}

sub numerical_bin_table {
    my ($bins,$labels,$incorrect,$correct,$count)=@_;
    my $table = 
        '<table><tr><th>'.&mt('Bar').'</th>'.
        '<th colspan="3">'.&mt('Range').'</th>'.
        '<th>'.&mt('Incorrect').'</th>'.
        '<th>'.&mt('Correct').'</th>'.
        '<th>'.&mt('Count').'</th>'.
        '</tr>'.$/;
    for (my $i=0;$i<scalar(@{$bins}-1);$i++) {
        my $lownum = $bins->[$i];
        if ($i == 0) { $lownum = '-&infin;'; }
        my $highnum = $bins->[$i+1];
        if ($i == scalar(@{$bins})-2) { $highnum = '&infin;'; }
        $table .= 
            '<tr>'.
            '<td>'.$labels->[$i].'</td>'.
            '<td align="right">'.$lownum.'</td>'.
            '<td>&nbsp;-&nbsp;</td>'.
            '<td align="right">'.$highnum.'</td>'.
            '<td align="right">'.$incorrect->[$i].'</td>'.
            '<td align="right">'.$correct->[$i].'</td>'.
            '<td align="right">'.$count->[$i].'</td>'.
            '</tr>'.$/;
    }
    $table.= '</table>';
    return $table;
}

sub numerical_determine_answers {
    my ($r,$resource,$partid,$respid,$students)=@_;
    my $c = $r->connection();
    #
    my %prog_state=&Apache::lonhtmlcommon::Create_PrgWin
        ($r,'Student Answer Compilation Status',
         'Student Answer Compilation Progress', scalar(@$students),
         'inline',undef,'Statistics','stats_status');
    #
    # Read in the cache (if it exists) before we start timing things.
    &Apache::lonstathelpers::ensure_proper_cache($resource->{'symb'});
    #
    my $correct;
    my %answers;
    foreach my $student (@$students) {
        last if ($c->aborted());
        my $sname = $student->{'username'};
        my $sdom = $student->{'domain'};
        # analyze problem
        my $analysis = 
            &Apache::lonstathelpers::analyze_problem_as_student($resource,
                                                                $sname,
                                                                $sdom);
        # make the key
        my $key = $partid.'.'.$respid;
	# pick one of the possible answers
	my $which = 'INTERNAL';
	if (!exists($analysis->{$key}{$which})) {
	    $which = (sort(keys(%{ $analysis->{$key} })))[0];
	}
        foreach my $item ('answer','unit','ans_high','ans_low') {
	    if (ref($analysis->{$key.'.'.$item}) eq 'ARRAY') {
		$correct->{$sname.':'.$sdom}->{$item} = 
		    $analysis->{$key.'.'.$item}[0];
	    } else {
		$correct->{$sname.':'.$sdom}->{$item} = 
		    $analysis->{$key.'.'.$item}{$which}[0][0];
	    }
        }
        $answers{$correct->{$sname.':'.$sdom}{'answer'}}++;
        &Apache::lonhtmlcommon::Increment_PrgWin($r,\%prog_state,
                                                 &mt('last student'));
    }
    &Apache::lonstathelpers::write_analysis_cache();
    &Apache::lonhtmlcommon::Close_PrgWin($r,\%prog_state);
    return ($correct,\%answers);
}

#
# Inputs: $r, $width, $height, $data
#         $n = number of students
#         $data = hashref of $answer => $frequency pairs
sub numerical_one_dimensional_plot {
    my ($r,$width,$height,$data)=@_;
    #
    # Compute data -> image scaling factors
    my $max_y = 0;
    my $min_x = undef;
    my $max_x = undef;
    my $n = 0;
    while (my ($answer,$count) = each(%$data)) {
        $n+=$count;
        $max_y = $count if ($max_y < $count);
        if (! defined($min_x) || $answer < $min_x) {
            $min_x = $answer;
        }
        if (! defined($max_x) || $answer > $max_x) {
            $max_x = $answer;
        }
    }
    #
    my $min_max_difference = $max_x - $min_x;
    if (! defined($min_max_difference) || $min_max_difference == 0) {
        $min_max_difference = 1;
    }
    my $h_scale = ($width-10)/$min_max_difference;
    #
    my $ticscale = 5;
    if ($max_y * $ticscale > $height/2) {
        $ticscale = int($height/2/$max_y);
        $ticscale = 1 if ($ticscale < 1);
    }
    #
    # Create the plot
    my $plot = 
        qq{<drawimage width="$width" height="$height" bgcolor="transparent" >};
    while (my ($answer,$count) = each(%$data)) {
        my $xloc = 5+$h_scale*($answer - $min_x);
        my $top    = $height/2-$count*$ticscale;
        my $bottom = $height/2+$count*$ticscale;
        $plot .= &line($xloc,$top,$xloc,$bottom,'888888',1);
    }
    #
    # Put the scale on last to ensure it is on top of the data.
    if ($min_x < 0 && $max_x > 0) {
        my $circle_x = 5+$h_scale*abs($min_x);  # '0' in data coordinates
        my $r = 4;
        $plot .= &line(5,$height/2,$circle_x-$r,$height/2,'000000',1);
        $plot .= &circle($circle_x,$height/2,$r+1,'000000');
        $plot .= &line($circle_x+$r,$height/2,$width-5,$height/2,'000000',1);
    } else {
        $plot .= &line(5,$height/2,$width-5,$height/2,'000000',1);
    }
    $plot .= '</drawimage>';
    my $plotresult =  &Apache::lonxml::xmlparse($r,'web',$plot);
    my $result = '<table>'.
        '<tr><td colspan="3" align="center">'.
        '<font size="+2">'.&mt('Distribution of correct answers').'</font>'.
        '<br />'.&mt('[_1] students, [_2] distinct correct answers',
                     $n,scalar(keys(%$data))).
        '<br />'.&mt('Maximum number of coinciding values: [_1]',$max_y).
        '</td></tr>'.
        '<tr>'.
        '<td valign="center">'.$min_x.'</td>'.
        '<td>'.$plotresult.'</td>'.
        '<td valign="center">'.$max_x.'</td>'.
        '</tr>'.
        '</table>';
    return $result;
}

##
## Helper subroutines for <drawimage>.  
## These should probably go somewhere more suitable soon.
sub line {
    my ($x1,$y1,$x2,$y2,$color,$thickness) = @_;
    return qq{<line x1="$x1" y1="$y1" x2="$x2" y2="$y2" color="$color" thickness="$thickness" />};
}

sub text {
    my ($x,$y,$color,$text,$font,$direction) = @_;
    if (! defined($font) || $font !~ /^(tiny|small|medium|large|giant)$/) {
        $font = 'medium';
    }
    if (! defined($direction) || $direction ne 'vertical') {
        $direction = '';
    }
    return qq{<text x="$x" y="$y" color="$color" font="$font" direction="$direction" >$text</text>};
}

sub rectangle {
    my ($x1,$y1,$x2,$y2,$color,$thickness,$filled) = @_;
    return qq{<rectangle x1="$x1" y1="$y1" x2="$x2" y2="$y2" color="$color" thickness="$thickness" filled="$filled" />};
}

sub arc {
    my ($x,$y,$width,$height,$start,$end,$color,$thickness,$filled)=@_;
    return qq{<arc x="$x" y="$y" width="$width" height="$height" start="$start" end="$end" color="$color" thickness="$thickness" filled="$filled" />};
}

sub circle {
    my ($x,$y,$radius,$color,$thickness,$filled)=@_;
    return &arc($x,$y,$radius,$radius,0,360,$color,$thickness,$filled);
}

#########################################################
#########################################################
##
##      Radio Response Routines
##
#########################################################
#########################################################
sub radio_response_analysis {
    my ($r,$problem,$problem_analysis,$students) = @_;
    #
    if ($env{'form.AnalyzeOver'} !~ /^(tries|time)$/) {
        $r->print('Bad request');
    }
    #
    my ($resource,$partid,$respid) = ($problem->{'resource'},
                                      $problem->{'part'},
                                      $problem->{'respid'});
    #
    my $analysis_html;
    my $foildata = $problem_analysis->{'_Foils'};
    my ($table,$foils,$concepts) = &build_foil_index($problem_analysis);
    if (! defined($concepts)) {
        $concepts = [];
    }
    #
    my %true_foils;
    my $num_true = 0;
    if (! $problem_analysis->{'answercomputed'}) {
        foreach my $foil (@$foils) {
            if ($foildata->{$foil}->{'value'} eq 'true') {
                $true_foils{$foil}++; 
            }
        }
        $num_true = scalar(keys(%true_foils));
    }
    #
    $analysis_html .= $table;
    # Gather student data
    my $response_data = &Apache::loncoursedata::get_response_data
        ([&Apache::lonstatistics::get_selected_sections()],
         [&Apache::lonstatistics::get_selected_groups()],
         $Apache::lonstatistics::enrollment_status,
         $resource->symb,$respid);
    my $correct;   # either a hash reference or a scalar
    if ($problem_analysis->{'answercomputed'} || scalar(@$concepts) > 1) {
        # This takes a while for large classes...
        &Apache::lonstathelpers::GetStudentAnswers($r,$problem,$students,
                                                   'Statistics',
                                                   'stats_status');
        foreach my $student (@$students) {
            my ($idx,@remainder) = split('&',$student->{'answer'});
            my ($answer) = ($remainder[$idx]=~/^(.*)=([^=]*)$/);
            $correct->{$student->{'username'}.':'.$student->{'domain'}}=
                &unescape($answer);
        }
    } else {
        foreach my $foil (keys(%$foildata)) {
            if ($foildata->{$foil}->{'value'} eq 'true') {
                $correct = $foildata->{$foil}->{'name'};
            }
        }
    }
    #
    if (! defined($response_data) || ref($response_data) ne 'ARRAY' ) {
        $analysis_html = '<div class="LC_warning">'
                        .&mt('There is no submission data for this resource.')
                        .'</div>';
        $r->print($analysis_html);
        return;
    }
    #
    $analysis_html.='<table>';
    for (my $plot_num = 1;$plot_num<=$env{'form.NumPlots'};$plot_num++) {
        # classify data ->correct foil -> selected foil
        my ($restriction_function,
            $correct_foil_title,$incorrect_foil_title,
            $pre_graph_text,$post_graph_text,
            $no_data_text,@extra_data);
        if ($env{'form.AnalyzeOver'} eq 'tries') {
            $restriction_function = sub {($_[0]->{'tries'} == $plot_num?1:0)};
            $correct_foil_title = 'Attempt '.$plot_num;
            $incorrect_foil_title = 'Attempt '.$plot_num;
            $pre_graph_text = 
                'Attempt [_1], [_2] submissions, [_3] correct, [_4] incorrect';
            $post_graph_text = '';
            $no_data_text = 'No data exists for attempt [_1]';
        } elsif ($env{'form.AnalyzeOver'} eq 'time') {
            my $starttime = &Apache::lonhtmlcommon::get_date_from_form
                ('startdate_'.$plot_num);
            my $endtime = &Apache::lonhtmlcommon::get_date_from_form
                ('enddate_'.$plot_num);
            ($starttime,$endtime) = &ensure_start_end_times
                ($starttime,$endtime,
                 &get_time_from_row($response_data->[0]),
                 &get_time_from_row($response_data->[-1]),
                 $plot_num);
            $pre_graph_text = 
                'Data from [_6] to [_7]'
               .'<br />'
               .'[_2] submissions from [_5] students, [_3] correct, [_4] incorrect';
            $extra_data[0] = &Apache::lonlocal::locallocaltime($starttime);
            $extra_data[1] = &Apache::lonlocal::locallocaltime($endtime);
            #
            $post_graph_text = 
                &mt('Start time: [_1]',
                    &Apache::lonhtmlcommon::date_setter
                    ('Statistics','startdate_'.$plot_num,$starttime)).
                '<br />'.
                &mt('End time: [_1]',
                    &Apache::lonhtmlcommon::date_setter
                    ('Statistics','enddate_'.$plot_num,$endtime));
            $restriction_function = 
                sub { 
                    my $t = $_[0]->{'timestamp'};
                    if ($t >= $starttime && $t < $endtime) {
                        return 1;
                    } else { 
                        return 0;
                    }
                };
            $no_data_text = 'No data for [_5] to [_6]';
        }
        my $foil_choice_data =
            &classify_response_data($response_data,$correct,
                                    $restriction_function);
        # &Apache::lonstathelpers::log_hash_ref($foil_choice_data);
        my $answers;
        if (ref($correct)) {
            my %tmp;
            foreach my $foil (values(%$correct)) {
                $tmp{$foil}++;
            }
            $answers = [keys(%tmp)];
        } else {
            $answers = [$correct];
        }
        # Concept Plot
        my $concept_plot = '';
        if (scalar(@$concepts) > 1) {
            $concept_plot = &RR_concept_plot($concepts,$foil_choice_data,
                                             'Correct Concepts');
        }
        # % Choosing plot
        my $choice_plot = &RR_create_percent_selected_plot
            ($concepts,$foils,$foil_choice_data,$correct_foil_title);
        # for each correct foil, how did they mark it? (stacked bar graph)
        my ($stacked_plot,$count_by_foil);
        if ($problem_analysis->{'answercomputed'} || $num_true > 1) {
            ($stacked_plot,$count_by_foil) =
                &RR_create_stacked_selection_plot($foils,$foil_choice_data,
                                                  $incorrect_foil_title,
                                                  \%true_foils);
        }
        #
        if ($concept_plot ne '' ||
            $choice_plot  ne '' ||
            $stacked_plot ne '') {
            my $correct = $foil_choice_data->{'_correct'};
            $correct |= 0;
            my $incorrect = $foil_choice_data->{'_count'}-$correct;
            $analysis_html.= '<tr><td colspan="4" align="center">'.
                '<font size="+1">'.
                &mt($pre_graph_text,
                    $plot_num,$foil_choice_data->{'_count'},
                    $correct,
                    $incorrect,
                    $foil_choice_data->{'_students'},
                    @extra_data).
                    '</td></tr>'.$/;
            $analysis_html.=
                '<tr>'.
                '<td>'.$concept_plot.'</td>'.
                '<td>'.$choice_plot.'</td>';
            if ($stacked_plot ne '') {
                $analysis_html .= 
                    '<td>'.$stacked_plot.'</td>'.
                    '<td>'.&build_foil_key($foils,$count_by_foil).'</td>';
            } else {
                $analysis_html .= ('<td></td>'x2);
            }
            $analysis_html.='</tr>'.$/;
            if (defined($post_graph_text)) {
                $analysis_html.= '<tr><td colspan="4" align="center">'.
                    $post_graph_text.'</td></tr>'.$/;
            }
        } elsif ($no_data_text ne '') {
            $analysis_html.='<tr><td colspan="4" align="center">'.
                '<div class="LC_warning">'.
                &mt($no_data_text,
                    $plot_num,$foil_choice_data->{'_count'},
                    $correct,                    
                    $foil_choice_data->{'_count'}-$correct,
                    @extra_data).
                '</div>';
            if (defined($post_graph_text)) {
                $analysis_html.='<br />'.$post_graph_text;
            }
            $analysis_html.='</td></tr>'.$/;
        }
    } # end of loop for plots
    $analysis_html.='</table>';
    $r->print($analysis_html);
}

sub ensure_start_end_times {
    my ($start,$end,$first,$last,$plot_num) = @_;
    if (! defined($start) || ! defined($end)) {
        my $sec_in_day = 86400;
        my ($sday,$smon,$syear) = 
            (localtime($last - $sec_in_day*($plot_num-1)))[3..5];
        $start = &Time::Local::timelocal(0,0,0,$sday,$smon,$syear);
        $end   = $start + $sec_in_day;
        if ($plot_num == $env{'form.NumPlots'}) {
            $start = $first;
        }
    }
    return ($start,$end);
}

sub RR_concept_plot {
    my ($concepts,$foil_data,$title) = @_;
    #
    my %correct_by_concept;
    my %incorrect_by_concept;
    my %true;
    foreach my $concept (@$concepts) {
        foreach my $foil (@{$concept->{'foils'}}) {
            next if (! exists($foil_data->{$foil}));
            foreach my $choice (keys(%{$foil_data->{$foil}})) {
                if ($choice eq $foil) {
                    $correct_by_concept{$concept->{'name'}} +=
                        $foil_data->{$foil}->{$choice};
                } else {
                    $incorrect_by_concept{$concept->{'name'}} +=
                        $foil_data->{$foil}->{$choice};
                }
            }
        }
    }
    # 
    # need arrays for incorrect and correct because we want to use different
    # colors for them
    my @correct;
    #
    my $total =0;
    for (my $i=0;$i<scalar(@$concepts);$i++) {
        my $concept = $concepts->[$i];
        $correct[$i]   =   $correct_by_concept{$concept->{'name'}};
        $total += $correct_by_concept{$concept->{'name'}}+
            $incorrect_by_concept{$concept->{'name'}};
    }
    if ($total == 0) { return ''; };
    for (my $i=0;$i<=$#correct;$i++) { 
        $correct[$i] = sprintf('%0f',$correct[$i]/$total*100);
    }
    my $xlabel = 'concept';
    my $plot=  &Apache::loncommon::DrawBarGraph($title,
                                                $xlabel,
                                                'Percent Choosing',
                                                100,
                                                ['#33ff00','#ff3300'],
                                                undef,
                                                \@correct);
    return $plot;
}

sub RR_create_percent_selected_plot {
    my ($concepts,$foils,$foil_data,$title) = @_;
    #
    if ($foil_data->{'_count'} == 0) { return ''; };
    my %correct_selections;
    my %incorrect_selections;
    foreach my $foil (@$foils) {
        # foil_data has format $foil_data->{true_foil}->{selected foil}=count
        next if (! exists($foil_data->{$foil}));
        while (my ($f,$count)= each(%{$foil_data->{$foil}})) {
            if ($f eq $foil) {
                $correct_selections{$foil} += $count;
            } else {
                $incorrect_selections{$f} += $count;
            }
        }
    }
    # 
    # need arrays for incorrect and correct because we want to use different
    # colors for them
    my @correct;
    my @incorrect;
    #
    my $total = $foil_data->{'_count'};
    for (my $i=0;$i<scalar(@$foils);$i++) {
        my $foil = $foils->[$i];
        $correct[$i]   = $correct_selections{$foil};
        $incorrect[$i] = $incorrect_selections{$foil};
    }
    for (my $i=0;$i<=$#correct;$i++) { 
        $correct[$i] = sprintf('%2f',$correct[$i]/$total*100);
    }
    for (my $i=0;$i<=$#incorrect;$i++) {
        $incorrect[$i] = sprintf('%2f',$incorrect[$i]/$total*100);
    }
    #
    # Put a blank in the data sets between concepts, if there are concepts
    my @labels;
    if (defined($concepts) && scalar(@$concepts) > 1) {
        my @new_correct;
        my @new_incorrect;
        my $foil_count = 0;
        foreach my $concept (@$concepts) {
            foreach (@{$concept->{'foils'}}) {
                push(@new_correct,  $correct[$foil_count]);
                push(@new_incorrect,$incorrect[$foil_count]);
                push(@labels,++$foil_count);
            }
            push(@new_correct,'');
            push(@new_incorrect,'');
            push(@labels,'');
        }
        @correct = @new_correct;
        @incorrect = @new_incorrect;
    } else {
        @labels = (1 .. scalar(@correct));
    }
    #
    my $xlabel = 'foil chosen';
    my $plot=  &Apache::loncommon::DrawBarGraph($title,
                                                $xlabel,
                                                'Percent Choosing',
                                                100,
                                                ['#33ff00','#ff3300'],
                                                \@labels,
                                                \@correct,
                                                \@incorrect);
    return $plot;
}

sub RR_create_stacked_selection_plot {
    my ($foils,$foil_data,$title,$true_foils)=@_;
    #
    my @dataset; # array of array refs - multicolor rows $datasets[row]->[col]
    my @labels;
    my $count;
    my %column; # maps foil name to column in @datasets
    for (my $i=0;$i<scalar(@$foils);$i++) {
        my $foil = $foils->[$i];
        if (defined($true_foils) && scalar(keys(%$true_foils)) > 0 ) {
            next if (! $true_foils->{$foil} );
            push(@labels,$i+1);
        } else {
            next if (! exists($foil_data->{$foil}));
            push(@labels,$i+1);
        }
        next if (! exists($foil_data->{$foils->[$i]}));
        $column{$foil}= $count++;
        for (my $j=0;$j<scalar(@$foils);$j++) {
            my $value = 0;
            if ($i != $j ) {
                $value += $foil_data->{$foil}->{$foils->[$j]};
            }
            $dataset[$j]->[$column{$foil}]=$value;
        }
    }
    #
    return '' if (! scalar(keys(%column)));
    #
    my $grand_total = 0;
    my %count_per_foil;
    while (my ($foil,$bar) = each (%column)) {
        my $bar_total = 0;
        for (my $j=0;$j<scalar(@dataset);$j++) {
            $bar_total += $dataset[$j]->[$bar];
        }
        next if ($bar_total == 0);
        for (my $j=0;$j<scalar(@dataset);$j++) {
            $dataset[$j]->[$bar] = 
                sprintf('%2f',$dataset[$j]->[$bar]/$bar_total * 100);
        }
        $count_per_foil{$foil}=' ( '.$bar_total.' )';
        $grand_total += $bar_total;
    }
    if ($grand_total == 0) {
        return ('',undef);
    }
    my @empty_row = ();
    foreach (@{$dataset[0]}) {
        push(@empty_row,0);
    }
    #
    my $graph = &Apache::loncommon::DrawBarGraph
        ($title,'Correct Foil','foils chosen Incorrectly',
         100,$plotcolors,\@labels,\@empty_row,@dataset);
    return ($graph,\%count_per_foil);
}


#########################################################
#########################################################
##
##       Misc routines
##
#########################################################
#########################################################

# if $correct is a hash ref, it is assumed to be indexed by student names.
#    the values are assumed to be hash refs with a key of 'answer'.
sub classify_response_data {
    my ($full_row_data,$correct,$function) = @_;
    my %submission_data;
    my %students;
    my $max=0;
    foreach my $row (@$full_row_data) {
        my %subm = &hashify_attempt($row);
        if (ref($correct) eq 'HASH') {
            $subm{'correct'} = $correct->{$subm{'student'}};
        } else {
            $subm{'correct'} = $correct;
        }
        $subm{'submission'} =~ s/=\d+\s*$//;
        if (&$function(\%subm)) {
            $students{$subm{'student'}}++;
            $submission_data{'_count'}++;
            if (&submission_is_correct($subm{'award'})) { 
                $submission_data{'_correct'}++;
            }
            
            if($max<++$submission_data{$subm{'correct'}}->{$subm{'submission'}}) {
                $max=$submission_data{$subm{'correct'}}->{$subm{'submission'}};
            }
        }
    }
    $submission_data{'_max'} = $max;
    $submission_data{'_students'}=scalar(keys(%students));
    return \%submission_data;
}


#########################################################
#########################################################
##
##      Option Response Routines
##
#########################################################
#########################################################
sub OptionResponseAnalysis {
    my ($r,$problem,$problem_data,$Students) = @_;
    my ($resource,$respid) = ($problem->{'resource'},
                              $problem->{'respid'});
    # Note: part data is not needed.
    my $PerformanceData = &Apache::loncoursedata::get_response_data
        ([&Apache::lonstatistics::get_selected_sections()],
         [&Apache::lonstatistics::get_selected_groups()],
         $Apache::lonstatistics::enrollment_status,
         $resource->symb,$respid);
    if (! defined($PerformanceData) || 
        ref($PerformanceData) ne 'ARRAY' ) {
        $r->print('<div class="LC_warning">'
                 .&mt('There is no student data for this problem.')
                 .'</div>'
        );
    }  else {
        $r->rflush();
        if ($env{'form.AnalyzeOver'} eq 'tries') {
            my $analysis_html = &OR_tries_analysis($r,
                                                   $PerformanceData,
                                                   $problem_data);
            $r->print($analysis_html);
            $r->rflush();
        } elsif ($env{'form.AnalyzeOver'} eq 'time') {
            my $analysis_html = &OR_time_analysis($PerformanceData,
                                                  $problem_data);
            $r->print($analysis_html);
            $r->rflush();
        } else {
            $r->print('div class="LC_warning"'
                     .&mt('The analysis you have selected is not supported at this time.')
                     .'</div>'
            );
        }
    }
}

#########################################################
#
#       Option Response:  tries Analysis
#
#########################################################
sub OR_tries_analysis {
    my ($r,$PerformanceData,$ORdata) = @_;
    my $mintries = 1;
    my $maxtries = $env{'form.NumPlots'};
    my ($table,$Foils,$Concepts) = &build_foil_index($ORdata);
    if (! defined($Concepts)) {
        $Concepts = [];
    }
    my %response_data = &OR_analyze_by_tries($r,$PerformanceData,
                                                     $mintries,$maxtries);
    my $analysis = '';
    #
    # Compute the data necessary to make the plots
    my @foil_plot; 
    my @concept_data;
    for (my $j=0;$j<=scalar(@$Concepts);$j++) {
        my $concept = $Concepts->[$j];
        foreach my $foilid (@{$concept->{'foils'}}) {
            for (my $try=$mintries;$try<=$maxtries;$try++) {
                # concept analysis data
                $concept_data[$j]->[$try]->{'_correct'} +=
                    $response_data{$foilid}->[$try]->{'_correct'};
                $concept_data[$j]->[$try]->{'_total'} +=
                    $response_data{$foilid}->[$try]->{'_total'};
                #
                # foil analysis data
                if ($response_data{$foilid}->[$try]->{'_total'} == 0) {
                    push(@{$foil_plot[$try]->{'_correct'}},0);
                } else {
                    push(@{$foil_plot[$try]->{'_correct'}},
                         100*$response_data{$foilid}->[$try]->{'_correct'}/
                         $response_data{$foilid}->[$try]->{'_total'});
                }
                foreach my $option (@{$ORdata->{'_Options'}}) {
                    push(@{$foil_plot[$try]->{'_total'}},
                         $response_data{$foilid}->[$try]->{'_total'});
                    if ($response_data{$foilid}->[$try]->{'_total'} == 0) {
                        push (@{$foil_plot[$try]->{$option}},0);
                    } else {
                        if ($response_data{$foilid}->[$try]->{'_total'} ==
                            $response_data{$foilid}->[$try]->{'_correct'}) {
                            push(@{$foil_plot[$try]->{$option}},0);
                        } else {
                            push (@{$foil_plot[$try]->{$option}},
                                  100 * 
                                  $response_data{$foilid}->[$try]->{$option} / 
                                  ($response_data{$foilid}->[$try]->{'_total'} 
                                   - 
                                   $response_data{$foilid}->[$try]->{'_correct'}
                                   ));
                        }
                    }
                } # End of foreach my $option
            }
        } # End of foreach my $foilid
    } # End of concept loops
    # 
    # Build a table for the plots
    my $analysis_html = "<br /><table>\n";
    my $optionkey = &build_option_index($ORdata);
    my $num_concepts = 1;
    if (defined($Concepts)) { $num_concepts = scalar(@$Concepts); }
    #
    for (my $try=$mintries;$try<=$maxtries;$try++) {
        if (! defined($response_data{'_total'}->[$try]) ||
            $response_data{'_total'}->[$try] == 0) { 
            if ($try > 1) {
                $analysis_html.= '<tr><td colspan="4">'
                                .'<div class="LC_info">'
                                .&mt('None of the selected students attempted the problem more than [_1] times.'
                                    ,$try-1)
                                .'</div>'
                                .'</td></tr>';
            } else {
                $analysis_html.= '<tr><td colspan="4">'
                                .'<div class="LC_info">'
                                .&mt('None of the selected students have attempted the problem.')
                                .'</div>'
                                .'</td></tr>';
            }
            last;
        }
        my $concept_graph='';
        if ($num_concepts > 1) {
            #
            # Create concept plot
            my @concept_plot_data;
            for (my $j=0;$j<=$#concept_data;$j++) {
                my $total = $concept_data[$j]->[$try]->{'_total'};
                if ($total == 0) {
                    $concept_plot_data[$j] = 0;
                } else {
                    $concept_plot_data[$j] = 100 * 
                        sprintf('%0.3f',
                                $concept_data[$j]->[$try]->{'_correct'} / 
                                $total);
                }
            }
            #
            $concept_graph = &Apache::loncommon::DrawBarGraph
                ('Correct Concepts','Concept Number','Percent Correct',
                 100,$plotcolors,undef,\@concept_plot_data,{xskip=>1});
        }
        #
        # Create Foil Plots
        my $data_count = $response_data{'_total'}->[$try];
        my $correct = $response_data{'_correct'}->[$try];
        $correct |= 0;
        my @Datasets;
        foreach my $option ('_correct',@{$ORdata->{'_Options'}}) {
            next if (! exists($foil_plot[$try]->{$option}));
            push(@Datasets,$foil_plot[$try]->{$option});
        }
        #
        # Put a blank in the data set between concepts
        for (my $set =0;$set<=$#Datasets;$set++) {
            my @Data = @{$Datasets[$set]};
            my $idx = 0;
            foreach my $concept (@{$Concepts}) {
                foreach my $foilid (@{$concept->{'foils'}}) {
                    $Datasets[$set]->[$idx++]=shift(@Data);
                }
                if ($concept->{'name'} ne $Concepts->[-1]->{'name'}) {
                    $Datasets[$set]->[$idx++] = 0;
                }
            }
        }
        #
        # Set up the labels needed for the bar graph
        my @Labels;
        my $idx = 1;
        foreach my $concept (@{$Concepts}) {
            foreach my $foilid (@{$concept->{'foils'}}) {
                push(@Labels,$idx++);
            }
            push(@Labels,'');
        }
        #
        my $correct_graph = &Apache::loncommon::DrawBarGraph
            ('Correct Statements','Statement','% Answered Correct',
             100,$plotcolors,\@Labels,$Datasets[0],{xskip=>1});
        
        #
        #
        next if (! defined($Datasets[0]));
        for (my $i=0; $i< scalar(@{$Datasets[0]});$i++) {
            $Datasets[0]->[$i]=0;
        }
        my $count = $response_data{'_total'}->[$try] - 
                                           $response_data{'_correct'}->[$try];
        my $incorrect_graph = &Apache::loncommon::DrawBarGraph
            ('Incorrect Statements','Statement','% Chosen Incorrectly',
             100,$plotcolors,\@Labels,@Datasets,{xskip=>1});
        $analysis_html.= 
            '<tr><td colspan="4" align="center">'.
            '<font size="+1">'.
            &mt('Attempt [_1], [_2] submissions, [_3] correct, [_4] incorrect',
                $try,$data_count,$correct,$data_count-$correct).
            '</font>'.'</td></tr>'.$/.                
            '<tr>'.
            '<td>'.$concept_graph.'</td>'.
            '<td>'.$correct_graph.'</td>'.
            '<td>'.$incorrect_graph.'</td>'.
            '<td>'.$optionkey.'<td>'.
            '</tr>'.$/;
    }
    $analysis_html .= "</table>\n";
    $table .= $analysis_html;
    return $table;
}

sub OR_analyze_by_tries {
    my ($r,$PerformanceData,$mintries,$maxtries) = @_;
    my %Trydata;
    $mintries = 1         if (! defined($mintries) || $mintries < 1);
    $maxtries = $mintries if (! defined($maxtries) || $maxtries < $mintries);
    my @students;
    foreach my $row (@$PerformanceData) {
        next if (! defined($row));
        my $tries = &get_tries_from_row($row);
        my %Row   = &Process_OR_Row($row);
        next if (! %Row);
        my $student_id = $row->[&Apache::loncoursedata::RD_student_id()];
        $students[$tries]->{$student_id}++;
        while (my ($foilid,$href) = each(%Row)) {
            if (! ref($href)) { 
                $Trydata{$foilid}->[$tries] += $href;
                next;
            }
            while (my ($option,$value) = each(%$href)) {
                $Trydata{$foilid}->[$tries]->{$option}+=$value;
            }
        }
    }
    for (my $try=$mintries;$try<=$maxtries;$try++) {
        $Trydata{'_studentcount'}->[$try] = scalar(keys(%{$students[$try]}));
    }
    return %Trydata;
}

#########################################################
#
#     Option Response: Time Analysis
#
#########################################################
sub OR_time_analysis {
    my ($performance_data,$ORdata) = @_;
    my ($table,$Foils,$Concepts) = &build_foil_index($ORdata);
    my $foilkey = &build_option_index($ORdata);
    my $num_concepts = 1;
    if (defined($Concepts)) { $num_concepts = scalar(@$Concepts); }
    #
    if ($num_concepts < 2) {
        $table = '<h3>'.
            &mt('Not enough data for concept analysis.  '.
                'Performing Foil Analysis').
                '</h3>'.$table;
    }
    #
    my $num_plots = $env{'form.NumPlots'};
    my $num_data = scalar(@$performance_data)-1;
    #
    my $current_index;
    $table .= "<table>\n";
    for (my $i=0;$i<$num_plots;$i++) {
        ##
        my $starttime = &Apache::lonhtmlcommon::get_date_from_form
            ('startdate_'.$i);
        my $endtime = &Apache::lonhtmlcommon::get_date_from_form
            ('enddate_'.$i);
        if (! defined($starttime) || ! defined($endtime)) {
            my $sec_in_day = 86400;
            my $last_sub_time = &get_time_from_row($performance_data->[-1]);
            my ($sday,$smon,$syear) = 
                (localtime($last_sub_time - $sec_in_day*$i))[3..5];
            $starttime = &Time::Local::timelocal(0,0,0,$sday,$smon,$syear);
            $endtime = $starttime + $sec_in_day;
            if ($i == ($num_plots -1 )) {
                $starttime = &get_time_from_row($performance_data->[0]);
            }
        }
        $table .= '<tr><td colspan="4" align="center"><font size="+1">'.
            &mt('Data from [_1] to [_2]',
                &Apache::lonlocal::locallocaltime($starttime),
                &Apache::lonlocal::locallocaltime($endtime)).
                '</font></td></tr>'.$/;
        my $startdateform = &Apache::lonhtmlcommon::date_setter
            ('Statistics','startdate_'.$i,$starttime);
        my $enddateform = &Apache::lonhtmlcommon::date_setter
            ('Statistics','enddate_'.$i,$endtime);
        #
        my $begin_index;
        my $end_index;
        my $j;
        while (++$j < scalar(@$performance_data)) {
            last if (&get_time_from_row($performance_data->[$j]) 
                                                              > $starttime);
        }
        $begin_index = $j;
        while ($j < scalar(@$performance_data)) {
            if (&get_time_from_row($performance_data->[$j]) > $endtime) {
                last;
            } else {
                $j++;
            }
        }
        $end_index = $j;
        ##
        my ($processed_time_data,$correct,$data_count,$student_count) =
            &OR_time_process_data($performance_data,$begin_index,$end_index);
        $correct |= 0;
        ##
        $table .= '<tr><td colspan="4" align="center"><font size="+1">'.
            &mt('[_1] submissions from [_2] students, [_3] correct, [_4] incorrect',
                $data_count,$student_count,$correct,$data_count-$correct).
                '</font></td></tr>'.$/;
        my $concept_correct_plot = '';
        if ($num_concepts > 1) {
            $concept_correct_plot = 
                &OR_Concept_Time_Analysis($processed_time_data,
                                          $correct,$data_count,$student_count,
                                          $ORdata,$Concepts);
        }
        my ($foil_correct_plot,$foil_incorrect_plot) = 
            &OR_Foil_Time_Analysis($processed_time_data,
                                   $correct,$data_count,$student_count,
                                   $ORdata,$Foils,$Concepts);
        $table .= '<tr>'.
            '<td>'.$concept_correct_plot.'</td>'.
            '<td>'.$foil_correct_plot.'</td>'.
            '<td>'.$foil_incorrect_plot.'</td>'.
            '<td align="left" valign="top">'.$foilkey.'</td></tr>'.$/;
        $table .= '<tr><td colspan="4" align="center">'.
            &mt('Start time: [_1]',$startdateform).'<br />'.
            &mt('End time: [_1]',$enddateform).'</td></tr>'.$/;
        $table.= '<tr><td colspan="4">&nbsp</td></tr>'.$/;
    }
    $table .= '</table>';
    #
    return $table;
}

sub OR_Foil_Time_Analysis {
    my ($processed_time_data,$correct,$data_count,$student_count,
        $ORdata,$Foils,$Concepts) = @_;
    if ($data_count <= 0) {
        return ('<div class="LC_warning">'
               .&mt('There is no data to plot.')
               .'</div>'
               ,''
        );
    }
    my $analysis_html;
    my @plotdata;
    my @labels;
    foreach my $concept (@{$Concepts}) {
        foreach my $foil (@{$concept->{'foils'}}) {
            push(@labels,scalar(@labels)+1);
            my $total = $processed_time_data->{$foil}->{'_total'};
            if ($total == 0) {
                push(@{$plotdata[0]},0);
            } else {
                push(@{$plotdata[0]},
                     100 * $processed_time_data->{$foil}->{'_correct'} / $total);
            }
            my $total_incorrect = $total - $processed_time_data->{$foil}->{'_correct'};
            for (my $i=0;$i<scalar(@{$ORdata->{'_Options'}});$i++) {
                my $option = $ORdata->{'_Options'}->[$i];
                if ($total_incorrect == 0) {
                    push(@{$plotdata[$i+1]},0);
                } else {
                    push(@{$plotdata[$i+1]},
                         100 * $processed_time_data->{$foil}->{$option} / $total_incorrect);
                }
            }
        }
        # Put in a blank one
        push(@labels,'');
        push(@{$plotdata[0]},0);
        for (my $i=0;$i<scalar(@{$ORdata->{'_Options'}});$i++) {
            push(@{$plotdata[$i+1]},0);
        }
    }
    #
    # Create the plot
    my $correct_plot = &Apache::loncommon::DrawBarGraph('Correct Statements',
                                                        'Statement Number',
                                                        'Percent Correct',
                                                        100,
                                                        $plotcolors,
                                                        undef,
                                                        $plotdata[0],
                                                        {xskip=>1});
    for (my $j=0; $j< scalar(@{$plotdata[0]});$j++) {
        $plotdata[0]->[$j]=0;
    }
    my $incorrect_plot = 
        &Apache::loncommon::DrawBarGraph('Incorrect Statements',
                                         'Statement Number',
                                         'Incorrect Option Choice',
                                         100,
                                         $plotcolors,
                                         undef,
                                         @plotdata,{xskip=>1});
    return ($correct_plot,$incorrect_plot);
}

sub OR_Concept_Time_Analysis {
    my ($processed_time_data,$correct,$data_count,$student_count,
        $ORdata,$Concepts) = @_;
    return '' if ($data_count == 0);
    #
    # Put the data in plottable form
    my @plotdata;
    foreach my $concept (@$Concepts) {
        my ($total,$correct);
        foreach my $foil (@{$concept->{'foils'}}) {
            $total += $processed_time_data->{$foil}->{'_total'};
            $correct += $processed_time_data->{$foil}->{'_correct'};
        }
        if ($total == 0) {
            push(@plotdata,0);
        } else {
            push(@plotdata,100 * $correct / $total);
        }
    }
    #
    # Create the plot
    return &Apache::loncommon::DrawBarGraph('Correct Concepts',
                                            'Concept Number',
                                            'Percent Correct',
                                            100,
                                            $plotcolors,
                                            undef,
                                            \@plotdata,{xskip=>1});
}

sub OR_time_process_data {
    my ($performance_data,$begin_index,$end_index)=@_;
    my %processed_time_data;
    my %distinct_students;
    my ($correct,$data_count);
    if (($begin_index == $end_index) && 
        ($end_index != scalar(@$performance_data)-1)) { 
        return undef;
    }
    # Be sure we include the last one if we are asked for it.
    # That we have to correct here (and not when $end_index is 
    # given a value) should probably be considered a bug.
    if ($end_index == scalar(@$performance_data)-1) {
        $end_index++;
    }
    my $count;
    for (my $i=$begin_index;$i<$end_index;$i++) {
        my $attempt = $performance_data->[$i];
        $count++;
        next if (! defined($attempt));
        my %attempt = &Process_OR_Row($attempt);
        $data_count++;
        $correct += $attempt{'_correct'};
        $distinct_students{$attempt->[&Apache::loncoursedata::RD_student_id()]}++;
        while (my ($foilid,$href) = each(%attempt)) {
            if (! ref($href)) {
                $processed_time_data{$foilid} += $href;
                next;
            }
            while (my ($option,$value) = each(%$href)) {
                $processed_time_data{$foilid}->{$option}+=$value;
            }
        }
    }
    return (\%processed_time_data,$correct,$data_count,
            scalar(keys(%distinct_students)));
}

sub build_foil_index {
    my ($ORdata) = @_;
    return if (! exists($ORdata->{'_Foils'}));
    my %Foildata = %{$ORdata->{'_Foils'}};
    my @Foils = sort(keys(%Foildata));
    my %Concepts;
    foreach my $foilid (@Foils) {
        push(@{$Concepts{$Foildata{$foilid}->{'_Concept'}}},
             $foilid);
    }
    undef(@Foils);
    # Having gathered the concept information in a hash, we now translate it
    # into an array because we need to be consistent about order.
    # Also put the foils in order, too.
    my $sortfunction = sub {
        my %Numbers = (one   => 1,
                       two   => 2,
                       three => 3,
                       four  => 4,
                       five  => 5,
                       six   => 6,
                       seven => 7,
                       eight => 8,
                       nine  => 9,
                       ten   => 10,);
        my $a1 = lc($a); 
        my $b1 = lc($b);
        if (exists($Numbers{$a1})) {
            $a1 = $Numbers{$a1};
        }
        if (exists($Numbers{$b1})) {
            $b1 = $Numbers{$b1};
        }
        if (($a1 =~/^\d+$/) && ($b1 =~/^\d+$/)) {
            return $a1 <=> $b1;
        } else {
            return $a1 cmp $b1;
        }
    };
    my @Concepts;
    foreach my $concept (sort $sortfunction (keys(%Concepts))) {
        if (! defined($Concepts{$concept})) {
            $Concepts{$concept}=[];
#            next;
        }
        push(@Concepts,{ name => $concept,
                        foils => [@{$Concepts{$concept}}]});
        push(@Foils,(@{$Concepts{$concept}}));
    }
    #
    # Build up the table of row labels.
    my $table = &Apache::loncommon::start_data_table();
    if (@Concepts > 1) {
        $table .= &Apache::loncommon::start_data_table_header_row().
            '<th>'.&mt('Concept Number').'</th>'.
            '<th>'.&mt('Concept').'</th>'.
            '<th>'.&mt('Foil Number').'</th>'.
            '<th>'.&mt('Foil Name').'</th>'.
            '<th>'.&mt('Foil Text').'</th>'.
            '<th>'.&mt('Correct Value').'</th>'.
            &Apache::loncommon::end_data_table_header_row();
    } else {
        $table .= &Apache::loncommon::start_data_table_header_row().
            '<th>'.&mt('Foil Number').'</th>'.
            '<th>'.&mt('Foil Name').'</th>'.
            '<th>'.&mt('Foil Text').'</th>'.
            '<th>'.&mt('Correct Value').'</th>'.
            &Apache::loncommon::end_data_table_header_row();
    }        
    my $conceptindex = 1;
    my $foilindex = 1;
    foreach my $concept (@Concepts) {
        my @FoilsInConcept = @{$concept->{'foils'}};
        my $firstfoil = shift(@FoilsInConcept);
        if (@Concepts > 1) {
            $table .= &Apache::loncommon::start_data_table_row().
                '<td>'.$conceptindex.'</td>'.
                '<td>'.&HTML::Entities::encode($concept->{'name'},'<>&"').'</td>'.
                '<td>'.$foilindex++.'</td>'.
                '<td>'.&HTML::Entities::encode($Foildata{$firstfoil}->{'name'},'<>&"').'</td>'.
                '<td>'.$Foildata{$firstfoil}->{'text'}.'</td>'.
                '<td>'.&HTML::Entities::encode($Foildata{$firstfoil}->{'value'},'<>&"').'</td>'.
                &Apache::loncommon::end_data_table_row();
        } else {
            $table .= &Apache::loncommon::start_data_table_row().
                '<td>'.$foilindex++.'</td>'.
                '<td>'.&HTML::Entities::encode($Foildata{$firstfoil}->{'name'},'<>&"').'</td>'.
                '<td>'.$Foildata{$firstfoil}->{'text'}.'</td>'.
                '<td>'.&HTML::Entities::encode($Foildata{$firstfoil}->{'value'},'<>&"').'</td>'.
                &Apache::loncommon::end_data_table_row();
        }
        foreach my $foilid (@FoilsInConcept) {
            if (@Concepts > 1) {
                $table .= &Apache::loncommon::start_data_table_row().
                    '<td></td>'.
                    '<td></td>'.
                    '<td>'.$foilindex.'</td>'.
                    '<td>'.&HTML::Entities::encode($Foildata{$foilid}->{'name'},'<>&"').'</td>'.
                    '<td>'.$Foildata{$foilid}->{'text'}.'</td>'.
                    '<td>'.&HTML::Entities::encode($Foildata{$foilid}->{'value'},'<>&"').'</td>'.
                    &Apache::loncommon::end_data_table_row();
            } else {
                $table .= &Apache::loncommon::start_data_table_row().
                    '<td>'.$foilindex.'</td>'.
                    '<td>'.&HTML::Entities::encode($Foildata{$foilid}->{'name'},'<>&"').'</td>'.
                    '<td>'.$Foildata{$foilid}->{'text'}.'</td>'.
                    '<td>'.&HTML::Entities::encode($Foildata{$foilid}->{'value'},'<>&"').'</td>'.
                    &Apache::loncommon::end_data_table_row();
            }                
        } continue {
            $foilindex++;
        }
    } continue {
        $conceptindex++;
    }
    $table .= &Apache::loncommon::end_data_table();
    #
    # Build option index with color stuff
    return ($table,\@Foils,\@Concepts);
}

sub build_option_index {
    my ($ORdata)= @_;
    my $table = "<table>\n";
    my $optionindex = 0;
    my @Rows;
    foreach my $option (&mt('correct option chosen'),@{$ORdata->{'_Options'}}) {
        my $color = $plotcolors->[$optionindex++];
        push (@Rows,
              '<tr>'.
              '<td bgcolor="'.$color.'">'.
              '<font color="'.$color.'">'.('*'x3).'</font>'.'</td>'.
              '<td>'.&HTML::Entities::encode($option,'<>&"').'</td>'.
              "</tr>\n");
    }
    shift(@Rows); # Throw away 'correct option chosen' color
    $table .= join('',reverse(@Rows));
    $table .= "</table>\n";
}

sub build_foil_key {
    my ($foils,$extra_data)= @_;
    if (! defined($extra_data)) { $extra_data = {}; }
    my $table = "<table>\n";
    my $foil_index = 0;
    my @rows;
    foreach my $foil (&mt('correct foil chosen'),@{$foils}) {
        my $color = $plotcolors->[$foil_index++];
        push (@rows,
              '<tr>'.
              '<td bgcolor="'.$color.'" class="key">'.
              '<font color="'.$color.'">'.('*'x4).'</font></td>'.
              '<td>'.&HTML::Entities::encode($foil,'<>&"').
              ('&nbsp;'x2).$extra_data->{$foil}.'</td>'.
              "</tr>\n");
    }
    shift(@rows); # Throw away 'correct foil chosen' color
    $table .= join('',reverse(@rows));
    $table .= "</table>\n";
}

#########################################################
#########################################################
##
##   Generic Interface Routines
##
#########################################################
#########################################################
sub CreateInterface {
    ##
    ## Environment variable initialization
    if (! exists($env{'form.AnalyzeOver'})) {
        $env{'form.AnalyzeOver'} = 'tries';
    }
    ##
    ## Build the menu
    my $Str = '';
    $Str .= &Apache::lonhtmlcommon::breadcrumbs('Detailed Problem Analysis');
    $Str .= '<p>';
    $Str .= &Apache::loncommon::start_data_table();
    $Str .= &Apache::loncommon::start_data_table_header_row();
    $Str .= '<th>'.&mt('Sections').'</th>';
    $Str .= '<th>'.&mt('Groups').'</th>';
    $Str .= '<th>'.&mt('Access Status').'</th>';
    $Str .= '<th>'.&mt('Options').'</th>';
    $Str .= &Apache::loncommon::end_data_table_header_row();
    ##
    ## 
    $Str .= &Apache::loncommon::start_data_table_row();
    $Str .= '<td align="center">'."\n";
    $Str .= &Apache::lonstatistics::SectionSelect('Section','multiple',5);
    $Str .= '</td>';
    #
    $Str .= '<td align="center">'."\n";
    $Str .= &Apache::lonstatistics::GroupSelect('Group','multiple',5);
    $Str .= '</td>';
    #
    $Str .= '<td align="center">';
    $Str .= &Apache::lonhtmlcommon::StatusOptions(undef,undef,5);
    $Str .= '</td>';
    #
    ##
    ##
    $Str .= '<td align="right" valign="top">';
    ##
    my $showprob_checkbox = 
        '<input type="checkbox" name="show_prob" value="true" ';
    if ($env{'form.show_prob'} eq 'true') {
        $showprob_checkbox .= 'checked="checked" ';
    }
    $showprob_checkbox.= ' />';
    $Str.= '<span class="LC_nobreak"><label>'.
        &mt('Show problem [_1]',$showprob_checkbox).
        '</label></span><br />';
    ##
    my $analyze_selector = '<select name="AnalyzeOver" >';
    $analyze_selector .= '<option value="tries" ';
    if (! exists($env{'form.AnalyzeOver'}) || 
        $env{'form.AnalyzeOver'} eq 'tries'){
        # Default to tries
        $analyze_selector .= ' selected="selected" ';
    }
    $analyze_selector .= '>'.&mt('Tries').'</option>';
    $analyze_selector .= '<option value="time" ';
    $analyze_selector .= ' selected ' if ($env{'form.AnalyzeOver'} eq 'time');
    $analyze_selector .= '>'.&mt('Time').'</option>';
    $analyze_selector .= '</select>';
    $Str .= '<span class="LC_nobreak"><label>'.
        &mt('Analyze Over [_1] [_2]',
            $analyze_selector,
            &Apache::loncommon::help_open_topic('Analysis_Analyze_Over')).
            '</label></span><br />'.$/;
    ##
    my $numplots_selector = '<select name="NumPlots">';
    if (! exists($env{'form.NumPlots'}) 
        || $env{'form.NumPlots'} < 1 
        || $env{'form.NumPlots'} > 20) {
        $env{'form.NumPlots'} = 5;
    }
    foreach my $i (1,2,3,4,5,6,7,8,10,15,20) {
        $numplots_selector .= '<option value="'.$i.'" ';
        if ($env{'form.NumPlots'} == $i) { $numplots_selector.=' selected="selected" '; }
        $numplots_selector .= '>'.$i.'</option>';
    }
    $numplots_selector .= '</select>';
    $Str .= '<span class="LC_nobreak"><label>'.&mt('Number of Plots [_1]',$numplots_selector).
        '</label></span><br />';
    ##
    $Str .= '</td>';
    ##
    ##
    $Str .= &Apache::loncommon::end_data_table_row();
    $Str .= &Apache::loncommon::end_data_table();
    $Str .= '<p class="LC_nobreak"><label>'
           .&mt('Status: [_1]',
                    '<input type="text" name="stats_status"'
                   .' size="60" value="" readonly="readonly" />')
           .'</label></p>';
    $Str .= '</p>';
    return $Str;
}

#########################################################
#########################################################
##
##              Misc Option Response functions
##
#########################################################
#########################################################
sub get_time_from_row {
    my ($row) = @_;
    if (ref($row)) {
        return $row->[&Apache::loncoursedata::RD_timestamp()];
    } 
    return undef;
}

sub get_tries_from_row {
    my ($row) = @_;
    if (ref($row)) {
        return $row->[&Apache::loncoursedata::RD_tries()];
    }
    return undef;
}

sub hashify_attempt {
    my ($row) = @_;
    my %attempt;
    $attempt{'student'}    = $row->[&Apache::loncoursedata::RD_sname()];
    $attempt{'tries'}      = $row->[&Apache::loncoursedata::RD_tries()];
    $attempt{'submission'} = &unescape($row->[&Apache::loncoursedata::RD_submission()]);
    $attempt{'award'}      = $row->[&Apache::loncoursedata::RD_awarddetail()];
    $attempt{'timestamp'}  = $row->[&Apache::loncoursedata::RD_timestamp()];
    return %attempt;
}

sub Process_OR_Row {
    my ($row) = @_;
    my %RowData;
#    my $student_id = $row->[&Apache::loncoursedata::RD_student_id()];
    my $award      = $row->[&Apache::loncoursedata::RD_awarddetail()];
    my $grading    = $row->[&Apache::loncoursedata::RD_response_eval()];
    my $submission = $row->[&Apache::loncoursedata::RD_submission()];
    my $time       = $row->[&Apache::loncoursedata::RD_timestamp()];
#    my $tries      = $row->[&Apache::loncoursedata::RD_tries()];
    return undef if ($award eq 'MISSING_ANSWER');
    if (&submission_is_correct($award)) {
        $RowData{'_correct'} = 1;
    }
    $RowData{'_total'} = 1;
    my @Foilgrades = split('&',$grading);
    my @Foilsubs   = split('&',$submission);
    for (my $j=0;$j<=$#Foilgrades;$j++) {
        my ($foilid,$correct)  = split('=',$Foilgrades[$j]);
        $foilid = &unescape($foilid);
        my (undef,$submission) = split('=',$Foilsubs[$j]);
        if ($correct) {
            $RowData{$foilid}->{'_correct'}++;
        } else {
            $submission = &unescape($submission);
            $RowData{$foilid}->{$submission}++;
        }
        $RowData{$foilid}->{'_total'}++;
    }
    return %RowData;
}

sub submission_is_correct {
    my ($award) = @_;
    if ($award =~ /(APPROX_ANS|EXACT_ANS)/) {
        return 1;
    } else {
        return 0;
    }
}

1;

__END__