File:  [LON-CAPA] / loncom / interface / lonstatistics.pm
Revision 1.29: download - view: text, annotated - select for diffs
Mon Jul 22 20:35:05 2002 UTC (21 years, 9 months ago) by stredwic
Branches: MAIN
CVS tags: HEAD
Lonchart is now part of lonstatistics.  When the CHRT button is pressed on
the remote control it will take you to the student assessment page.  In
the next commit or two, the student assessment page and lonchart will
gradually merge, or I will make chart its own report.

I added another perl module, lonhtmlcommon which will contain a series of
functions that create controls and data layouts for various different
pieces of information.  This is just a fledgling module.

The biggest feature of this commit is that the downloading of student course
data has changed slightly.  Now, the classlist will contain all students,
but will only display the appropriate ones.  Different reports require
different amounts of data, so some may only download student course data
when selected and some will download it all at once.  The downloading
will first grab the time stamp on the course.db file for the student and
compare it will the cached timestamp for that file.  It will only do a
dump if the data is not yet cached or the timestamp is newer than the one
stored.  Only when the data is processed is the timestamp update, not
when downloaded.  The Download/Process duo of function work hand in hand.
Calling both will be typical even if there was nothing actually downloaded.

The is now a new form, which is a class list with different information.
This list also contain the timestamp for each student, when their course
data was downloaded last.  Having this page is both informational, and
hopefully will mean that it is not necessary for all the other pages, at least
as defaults.

Each report now has a common header.  There is currently some white space,
but it can be filled.  The header has a refresh button, update all student
data button, a selection of forms and a selection of student status.  The
update all student data button will download all students (active and expired)
for the given course.  This allows someone to come to the entry page(
class list) update all the students while they do stuff and come back.
The two selection boxes are special in that they will update the
document when changed.  The onchange attribute was tested on mac,
linux and pc, for the different browsers.  The only noticed difference
was netscape 4.7 executes the javascript if it you select the same thing,
where all others do not.  Also, the same browser causes the first
button in the form to be pressed when the document.form.submit()
javascript is executed for the onchange of the selection box.

There was other cosmetic changes, but were minor.

# The LearningOnline Network with CAPA
# (Publication Handler
#
# $Id: lonstatistics.pm,v 1.29 2002/07/22 20:35:05 stredwic 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/
#
# (Navigate problems for statistical reports
# YEAR=2001
# 5/5,7/9,7/25/1,8/11,9/13,9/26,10/5,10/9,10/22,10/26 Behrouz Minaei
# 11/1,11/4,11/16,12/14,12/16,12/18,12/20,12/31 Behrouz Minaei
# YEAR=2002
# 1/22,2/1,2/6,2/25,3/2,3/6,3/17,3/21,3/22,3/26,4/7,5/6 Behrouz Minaei
# 5/12,5/14,5/15,5/19,5/26,7/16  Behrouz Minaei
#
###

package Apache::lonstatistics; 

use strict; 
use Apache::Constants qw(:common :http);
use Apache::lonnet();
use Apache::lonhomework;
use Apache::loncommon;
use Apache::loncoursedata;
use Apache::lonhtmlcommon;
use Apache::lonchart;
use HTML::TokeParser;
use GDBM_File;

# -------------------------------------------------------------- Module Globals
my %hash;
my %CachData;
my %GraphDat;
my $r;
my $GData;
my %color;
my %foil_to_concept;
my @Concepts;
my %ConceptData;
my %Answer=();
my %mapsort;

my %Activity=();
my %Grade=();
my %DoDiff=();
my %Discuss=();
my $TotalDiscuss=0;
my $TotalDiscuss_=0;


sub LoadDiscussion {
#    my $symb=shift;
#    $r->print('<br>$cid ... '.$symb);
#    my %contrib=&Apache::lonnet::dump('msu_2964385f9033c63msul1','msu','2964385f9033c63msul1');
    my $cid=$ENV{'request.course.id'};
    my %contrib=&Apache::lonnet::dump(
                $ENV{'request.course.id'},
                $ENV{'course.'.$ENV{'request.course.id'}.'.domain'},
                $ENV{'course.'.$ENV{'request.course.id'}.'.num'});
				                            
    foreach my $temp(keys %contrib) {
	if ($temp=~/^version/) {
	    my $ver=$contrib{$temp};
	    my ($dummy,$prb)=split(':',$temp);
	    for (my $idx=1; $idx<=$ver; $idx++ ) {
		my $name=$contrib{"$idx:$prb:sendername"};
		$Discuss{"$name:$prb"}=$idx;	
	    }
	}
    }       
#   $r->print('<br>cid='.$cid);
#    my %contrib=&Apache::lonnet::restore($symb,$cid,
#					 $ENV{$cid.'.domain'},
#					 $ENV{'course.'.$cid.'.num'});

#    $Apache::lonxml::debug=1;
#    &Apache::lonhomework::showhash(%Discuss);
#    $Apache::lonxml::debug=0;
}

sub LoadDoDiffFile {
    my $file="/home/minaeibi/183d.txt";
    open(FILEID, "<$file");
    my $line=<FILEID>;
    %DoDiff=();
    my @Act=split('&',$line);
    
#    $r->print('<br>'.$#Act);
    for(my $n=0;$n<=$#Act;$n++){
       my ($res,$Degree)=split('@',$Act[$n]);
      $DoDiff{$res}=$Degree;
    }
}


sub LoadClassFile {
    my $file="/home/minaeibi/class.txt";
    open(FILEID, "<$file");
    my $line;
    %Grade=();
    while ($line=<FILEID>) {
        my ($id,$ex1,$ex2,$ex3,$ex4,$hw,$final,$grade)=split(' ',$line);
        $Grade{$id}=$grade;
    }
}


#------- Classification  
sub Classify {
    my ($DiscFac, $students)=@_;
    &LoadClassFile();
    my $Count=0;
    my @List=();
    my @LS=();
    my @LF=();
    my @LM=();
    my $cf=0;
    my $cs=0;
    my $cm=0;
    foreach (keys(%$DiscFac)){  
	my @l=split(/\:/,$_);
	if (!($students->{$l[1]})) {next;}
	my $Grade=$Grade{$students->{$l[1]}};
	if( $Grade > 3 ) {
	    $cs++;
	    push(@LS,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Successful"));
	} elsif ( $Grade > 2 ) {
	    $cm++;
	    push(@LM,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Average"));
	} else {
	    $cf++;
	    push(@LF,("$l[6],$l[5],$l[4],$l[7],$l[8],$l[9],Failed"));
	}
    }    
    for(my $n=0;$n<$cs;$n++){$r->print('<br>'.$LS[$n]);}
    for(my $n=0;$n<$cm;$n++){$r->print('<br>'.$LM[$n]);}  
    for(my $n=0;$n<$cf;$n++){$r->print('<br>'.$LF[$n]);}
} 


sub ProcAct {
    # return;
    my ($Act,$Submit)=@_;
    my @Act=split(/\@/,$Act);
    @Act = sort(@Act);

    ##$r->print('<br>'.$#Act);
    ##for(my $n=0;$n<=$#Act;$n++){
##	$r->print('<br>n='.$n.')'.$Act[$n]);
##    }

#    my $Beg=$Act[0];
    my $Dif=$Submit-$Act[0];
    $Dif = ($Dif>0) ? ($Dif/3600) : 0; 

#    $r->print('<br>Access Number = '.$#Act.'<br>Submit Time='.$Submit.'<br>First Access='.$Act[0].'<br>Last Access='.$Act[$#Act].'<br> Submit - First = <b>'.$Dif.'</b>');


#time spent for solving the problem           
#    $r->print('<br>Def'.($Act[$#Act-1]-$Act[0]));

    return $Dif;
}



sub LoadActivityLog {
#    my $CacheDB = "/home/minaeibi/act183.log.cache";
    my $CacheDB = "/home/httpd/perl/tmp/act183.log.cache";
    
    if (-e "$CacheDB") {
	if (tie(%Activity,'GDBM_File',"$CacheDB",&GDBM_READER,0640)) {
	    return;
        }
        else {
	    $r->print("Unable to tie log Cache hash to db file");
        }
    }
    else {
	if (tie(%Activity,'GDBM_File',$CacheDB,&GDBM_WRCREAT,0640)) {
	    foreach (keys %Activity) {delete $Activity{$_};}
	    &Build_log(); 
	}
        else {
	    $r->print("Unable to tie log Build hash to db file");
        }
    }
}

sub Build_log {
    my $file="/home/minaeibi/act183.log";
    open(FILEID, "<$file");
    my $line;
    my $count=0;
    while ($line=<FILEID>) {
	my ($time,$machine,$what)=split(':',$line);
	$what=&Apache::lonnet::unescape($what);
	my @accesses=split('&',$what);
	           
	foreach my $access (@accesses) {

	    $count++;

	    my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
	    if (!$resource) { next; }
	    my $res=&Apache::lonnet::unescape($resource);
	    if (($res =~ /\.problem/)) {
		$Activity{$who.':'.$res}.=$date.'@';
                #$r->print('<br>'.$time.':'.$who.'---'.$res);
		&Update_PrgInit($count);

	    }
	}
    }

# my $c=1;
# foreach (sort keys %Activity) {
#     $r->print('<br>'.$c.')'.$_.' ... '.$Activity{$_});
#     $c++;
# }

}

sub Activity {
#    $rid=~/(\d+)\.(\d+)/;
#    my $MapId=$1;
#    my $PrbId=$2;
#    my $MapOrg = $hash{'map_id_'.$MapId};
#    my $Map = &Apache::lonnet::declutter($MapOrg);
#    my $URI = $hash{'src_'.$rid};
#    my $Symb = $Map.'___'.$PrbId.'___'.&Apache::lonnet::declutter($URI);
    my $file="/home/minaeibi/activity.log";
    my $userid='adamsde1';
    $r->print("<br>Using $file");
    $r->rflush();
    open(FILEID, "<$file");
    my $line;
    my @allaccess;
    my $Count=0;
    while ($line=<FILEID>) {
	my ($time,$machine,$what)=split(':',$line);
	$what=&Apache::lonnet::unescape($what);
	my @accesses=split('&',$what);
	foreach my $access (@accesses) {
	    my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
	    #if ($who ne $userid) { next; }
	    if (!$resource) { next; }
	    my $res=&Apache::lonnet::unescape($resource);
	    if (($res =~ /\.(sequence|problem|htm|html|page)/)) {
	    	$Count++;
		$r->print("<br>$Count) ".localtime($date).": $who --> $res");
#	        if ($post) { 
#		    $Count++;
#		    $r->print("<br><b>$Count) Sent data ".join(':',
#                              &Apache::lonnet::unescape(@posts)).'</b>');
#		}
		$r->rflush();
	    }
	    #push (@allaccess,unescape($access));
	    #print $machine;
	}
    }
#    @allaccess=sort(@allaccess);
#    $Count=0;
#    foreach my $access (@allaccess) {
#	my ($date,$resource,$who,$domain,$post,@posts)=split(':',$access);
#	$Count++;
#	$r->print("<br>$Count) $date: $who --> $resource");
#	$r->rflush();
#	if ($post) { 
#	    $r->print("<br><b>Sent data ".join(':',unescape(@posts)).'</b>');
#	}
#    }
}


sub InitAnalysis {
    my ($uri,$part,$problem,$student,$courseID)=@_;
    my ($uname,$udom)=split(/\:/,$student);


    # Render the student's view of the problem.  $Answ is the problem 
    # Stringafied
    my $Answ=&Apache::lonnet::ssi($uri,('grade_target' => 'analyze',
                                  'grade_username' => $uname,
                                  'grade_domain' => $udom,
                                  'grade_courseid' => $courseID,
                                  'grade_symb' => $problem));
#    my $Answ=&Apache::lonnet::ssi($URI,('grade_target' => 'analyze'));

#    (my $garbage,$Answ)=split(/_HASH_REF__/,$Answ,2);
    %Answer=();
    %Answer=&Apache::lonnet::str2hash($Answ);

    my $parts='';
    foreach my $elm (@{$Answer{"parts"}}) {
	$parts.="$elm,";
    }
    chop($parts);
    my $conc='';
    foreach my $elm (@{$Answer{"$parts.concepts"}}) {
	$conc.="$elm@";
    }
    chop($conc);

    @Concepts=split(/\@/,$conc);
    foreach my $concept (@{$Answer{"$parts.concepts"}}) {
	foreach my $foil (@{$Answer{"$parts.concept.$concept"}}) {
	    $foil_to_concept{$foil} = $concept;
	    #$ConceptData{$foil} = $Answer{"$parts.foil.value.$foil"};
	}
    }

    return;
}


sub Interval {
    my ($part,$symb)=@_;
    my $Int=$ConceptData{"Interval"};
    my $due = &Apache::lonnet::EXT('resource.$part.duedate',$symb)+1;
    my $opn = &Apache::lonnet::EXT('resource.$part.opendate',$symb);
    my $add=int(($due-$opn)/$Int);
    $ConceptData{"Int.0"}=$opn;
    for (my $i=1;$i<$Int;$i++) {
	$ConceptData{"Int.$i"}=$opn+$i*$add;
    }
    $ConceptData{"Int.$Int"}=$due;     
    for (my $i=0;$i<$Int;$i++) {
	for (my $n=0; $n<=$#Concepts; $n++ ) {
	    my $tmp=$Concepts[$n];
	    $ConceptData{"$tmp.$i.true"}=0;
	    $ConceptData{"$tmp.$i.false"}=0;
	}
    }
}


sub ShowOpGraph {
    my ($cache, $students, $courseID)=@_;
    my $uri      = $cache->{'AnalyzeURI'};
    my $part     = $cache->{'AnalyzePart'};
    my $problem  = $cache->{'AnalyzeProblem'};
    my $title    = $cache->{'AnalyzeTitle'};
    my $interval = $cache->{'Interval'};
    $ConceptData{"Interval"} = $interval;

    #Initialize the option response true answers
    &InitAnalysis($uri, $part, $problem, $students->[0],$courseID);

    #compute the intervals
    &Interval($part,$problem);

    $title =~ s/\ /"_"/eg;
    $r->print('<br><b>'.$uri.'</b>');
    $r->rflush();
         
    #Java script Progress window
    &Create_PrgWin();
    &Update_PrgWin("Starting-to-analyze-problem");
    for (my $index=0;$index<(scalar @$students);$index++) {
	&Update_PrgWin($index);
	&OpStatus($problem,$students->[$index],$courseID);
    }
    &Close_PrgWin();

    $r->print('<br>');
    for (my $k=0; $k<$interval; $k++ ) {
	&DrawGraph($k,$title);
    }
    for (my $k=0; $k<$interval; $k++ ) {
	&DrawTable($k);
    }
#$Apache::lonxml::debug=1;
#&Apache::lonhomework::showhash(%ConceptData);
#$Apache::lonxml::debug=0;
    my $Answ=&Apache::lonnet::ssi($uri);
    $r->print("<br><b>Here you can see the Problem:</b><br>$Answ");
}


sub DrawTable {
    my $k=shift;
    my $Max=0;
    my @data1;
    my @data2;
    my $Correct=0;
    my $Wrong=0;
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	my $tmp=$Concepts[$n];
	$data1[$n]=$ConceptData{"$tmp.$k.true"};
	$Correct+=$data1[$n];
	$data2[$n]=$ConceptData{"$tmp.$k.false"};
	$Wrong+=$data2[$n];
	my $Sum=$data1[$n]+$data2[$n];
	if ( $Max<$Sum ) {$Max=$Sum;}
    }
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	if ($data1[$n]+$data2[$n]<$Max) {
	    $data2[$n]+=$Max-($data1[$n]+$data2[$n]);
	}
    }
    my $P_No = $#data1+1;
#    $r->print('<br><b>From: ['.localtime($ConceptData{'Int.'.($k-1)}).
#              '] To: ['.localtime($ConceptData{"Int.$k"}).']</b>'); 
    my $Str = "\n".'<table border=2>'.
              "\n".'<tr>'.
              "\n".'<th> # </th>'.
	      "\n".'<th> Concept </th>'.
	      "\n".'<th> Correct </th>'.
	      "\n".'<th> Wrong </th>'.
	      "\n".'</tr>';

    for (my $n=0; $n<=$#Concepts; $n++ ) {
	$Str .= "\n"."<tr>".
	        "\n"."<td>".($n+1)."</td>".
                "\n".'<td bgcolor='.$color{"yellow"}.'> '.$Concepts[$n]." </td>".
                "\n".'<td bgcolor='.$color{"green"}.'> '.$data1[$n]." </td>".
                "\n".'<td bgcolor='.$color{"red"}.'> '.$data2[$n]." </td>".
                "\n"."</tr>";
    }
    $Str.='<td></td><td><b>From:['.localtime($ConceptData{'Int.'.$k}).
          '] To: ['.localtime($ConceptData{'Int.'.($k+1)}-1).
          "]</b></td><td>$Correct</td><td>$Wrong</td>";

    $Str .= "\n".'</table>';

    $r->print($Str);
#$Apache::lonxml::debug=1;
#&Apache::lonhomework::showhash(%ConceptData);
#$Apache::lonxml::debug=0;
}


sub DrawGraph {
    my ($k,$Src)=@_;
    my $Max=0;
    my @data1;
    my @data2;

    # Adjust Data and find the Max 
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	my $tmp=$Concepts[$n];
	$data1[$n]=$ConceptData{"$tmp.$k.true"};
	$data2[$n]=$ConceptData{"$tmp.$k.false"};
	my $Sum=$data1[$n]+$data2[$n];
	if ( $Max<$Sum ) {$Max=$Sum;}
    }
    for (my $n=0; $n<=$#Concepts; $n++ ) {
	if ($data1[$n]+$data2[$n]<$Max) {
	    $data2[$n]+=$Max-($data1[$n]+$data2[$n]);
	}
    }
    my $P_No = $#data1+1;

    if ( $Max > 1 ) { 
	$Max += (10 - $Max % 10);
	$Max = int($Max);
    } else { $Max = 1; }

    my $Titr=($ConceptData{'Interval'}>1) ? $Src.'_interval_'.($k+1) : $Src;
#    $GData=$Titr.'&Concepts'.'&'.'Answers'.'&'.$Max.'&'.$P_No.'&'.$data1.'&'.$data2;
    $GData="$Titr&Concepts&Answers&$Max&$P_No&".
           (join(',',@data1)).'&'.(join(',',@data2));

    $r->print('<IMG src="/cgi-bin/graph.gif?'.$GData.'" border=1/>');
}


sub Decide {
    #deciding the true or false answer belongs to each interval
    my ($type,$foil,$time)=@_; 
    my $k=0;
    while ($time>$ConceptData{'Int.'.($k+1)} && 
           $k<$ConceptData{'Interval'}) {$k++;}
    $ConceptData{"$foil_to_concept{$foil}.$k.$type"}++;
}

#restore the student submissions and finding the result
sub OpStatus {
    my ($problem, $student, $courseID)=@_;
    my ($username,$userdomain)=split(/':'/,$student);
    my $code='U';
    my %reshash=&Apache::lonnet::restore($problem, $courseID, $userdomain, 
                                         $username);
    my @True = ();
    my @False = ();
    my $flag=0;
    if ($reshash{'version'}) {
        my $tries=0;
	&Apache::lonhomework::showhash(%Answer);
	for (my $version=1;$version<=$reshash{'version'};$version++) {
	    my $time=$reshash{"$version:timestamp"};
	   
	    foreach my $key (sort(split(/\:/,$reshash{$version.':keys'}))) {
		if (($key=~/\.(\w+)\.(\w+)\.submission$/)) {
		    my $Id1 = $1; my $Id2 = $2;
		    #check if this is a repeat submission, if so skip it
          	    if ($reshash{"$version:resource.$Id1.previous"}) { next; }
		    #if no solved this wasn't a real submission, ignore it
		    if (!defined($reshash{"$version:resource.$Id1.solved"})) {
			&Apache::lonxml::debug("skipping ");
			next;
		    }
		    my $Resp = $reshash{"$version:$key"};
		    my %submission=&Apache::lonnet::str2hash($Resp);
		    foreach (keys %submission) {
			my $Ansr = $Answer{"$Id1.$Id2.foil.value.$_"};
			if ($submission{$_}) {
			    if ($submission{$_} eq $Ansr) {
				&Decide("true",$_,$time );
			    }
			    else {&Decide("false",$_,$time );}
			}
		    }
	        }	  
	    }
        }
    }
}


#---- END Analyze Web Page ----------------------------------------------

#---- Problem Statistics Web Page ---------------------------------------

#------- Processing upperlist and lowerlist according to each problem
sub ProcessDiscriminant {
    my ($List) = @_;
    my @sortedList = sort (@$List);
    my $Count = scalar @sortedList;
    my $Problem;
    my @Dis;
    my $Slvd=0;
    my $tmp;
    my $Sum1=0;
    my $Sum2=0;
    my $nIndex=0;
    my $nStudent=0;
    my %Proc=undef;
    while ($nIndex<$Count) {
	($Problem,$tmp)=split(/\=/,$sortedList[$nIndex]);
	@Dis=split(/\+/,$tmp);
	my $Temp = $Problem;
	do {
	    $nIndex++;
	    $nStudent++;
	    $Sum1 += $Dis[0];
	    $Sum2 += $Dis[1];
	    ($Problem,$tmp)=split(/\=/,$sortedList[$nIndex]);
	    @Dis=split(/\+/,$tmp);
	} while ( $Problem eq $Temp && $nIndex < $Count );
#	$Proc{$Temp}=($Sum1/$nStudent).':'.$nStudent;
	$Proc{$Temp}=($Sum1/$nStudent).':'.($Sum2/$nStudent);
#       $r->print("$nIndex) $Temp --> ($nStudent) $Proc{$Temp} <br>");
	$Sum1=0;
	$Sum2=0;
	$nStudent=0;
    }

    return %Proc;
}



#------- Creating Discimination factor   
sub Discriminant {
    my ($discriminantFactor)=@_;
    my @discriminantKeys=keys(%$discriminantFactor);
    my $Count = scalar @discriminantKeys;

    my $UpCnt = int(0.27*$Count);
    my $low=0;
    my $up=$Count-$UpCnt;
    my @UpList=();
    my @LowList=();

    $Count=0;
    foreach my $key (sort(@discriminantKeys)) { 
	$Count++;    
	if($low < $UpCnt || $Count > $up) {
            $low++;
            my $str=$discriminantFactor->{$key};
            foreach(split(/\:/,$str)){
                if($_) {
                    if($low<$UpCnt) { push(@LowList,$_); }
                    else            { push(@UpList,$_);  }
                }
            }
        }
    }
    my %DisUp =  &ProcessDiscriminant(\@UpList);
    my %DisLow = &ProcessDiscriminant(\@LowList);

    return (\%DisUp, \%DisLow);
}

   
sub NumericSort {          
    $a <=> $b;
}


sub CreateProblemStatisticsTableHeading {
    my ($displayFormat,$sequenceSource,$sequenceTitle,$headings)=@_;
    if($displayFormat eq 'Display CSV Format') {
        $r->print('<br>"'.$sequenceTitle.'","');
        $r->print($sequenceSource.'"');
	return;
    }

    $r->print('<br><a href="'.$sequenceSource.
              '" target="_blank">'.$sequenceTitle.'</a>');

    my $Result = "\n".'<table border=2><tr><th>P#</th>'."\n";
    for(my $nIndex=0; $nIndex < (scalar (keys %$headings)); $nIndex++) { 
	$Result .= '<th>'.'<input type="submit" name="';
        $Result .= 'ProblemStatisticsHeading" value="';
        $Result .= $headings->{$nIndex}.'" />'.'</th>'."\n";
    }
    $Result .= "\n".'</tr>'."\n";    
    $r->print($Result);
    $r->rflush();
}

sub CloseTable {
    my ($cache)=@_;
    if($cache->{'DisplayFormat'} eq 'Display CSV Format') {
	return;
    }    
    $r->print("\n".'</table>'."\n");
    $r->rflush();
}


 
# ------ Dump the Student's DB file and handling the data for statistics table 
sub ExtractStudentData {
    my ($cache,$name,$list)=@_;
    my %discriminantFactor;

    my $totalTries = 0;
    my $totalAwarded = 0;
    my $tempProblemOrder=0;
    my $spent=0;
    my $spent_yes=0;
    my $TotDiscuss=0;
    my $TotalOpend = 0;
    my $ProbSolved = 0;
    my $ProbTot = 0;
    my $TotFirst = 0;
    my $TimeTot = 0;
    my $Discussed=0;

    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
        if($cache->{'ProblemStatisticsMap'} ne 'All Maps'  &&
           $cache->{'ProblemStatisticsMap'} ne $cache->{$sequence.':title'}) {
            next;
        }

        my $Dis = '';
        foreach my $problemID (split(':', $cache->{$sequence.':problems'})) {
            my $problem = $cache->{$problemID.':problem'};
            my $LatestVersion = $cache->{$name.':version:'.$problem};

            # Output dashes for all the parts of this problem if there
            # is no version information about the current problem.
            #if(!$LatestVersion) {
            #    foreach my $part (split(/\:/,$cache->{$sequence.':'.
            #                                          $problemID.
            #                                          ':parts'})) {
            #        $codes    .= "-,";
            #        $attempts .= "0,"; 
            #    }
            #    next;
            #}

            my %partData=undef;
            # Initialize part data, display skips correctly
            # Skip refers to when a student made no submissions on that
            # part/problem.
            foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                  $problemID.
                                                  ':parts'})) {
                $partData{$part.':tries'}=0;
                $partData{$part.':code'}='-';
            }

            # Looping through all the versions of each part, starting with the
            # oldest version.  Basically, it gets the most recent 
            # set of grade data for each part.
	    for(my $Version=1; $Version<=$LatestVersion; $Version++) {
                foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                      $problemID.
                                                      ':parts'})) {

                    if(!defined($cache->{$name.":$Version:$problem".
                                               ":resource.$part.solved"})) {
                        # No grade for this submission, so skip
                        next;
                    }

                    my $tries=0;
                    my $time=0;
                    my $awarded=0;
		    $Discussed=0;
                    my $code='U';

                    $awarded = $cache->{$name.
                                        "$Version:$problem:resource.".
                                        "$part.awarded"};
                    $partData{$part.':awarded'} = ($awarded) ? $awarded : 0;
                    $totalAwarded += $awarded;

                    $tries = $cache->{$name.":$Version:$problem".
                                      ":resource.$part.tries"};
                    $partData{$part.':tries'} = ($tries) ? $tries : 0;
                    $partData{$part.':wrong'} = $partData{$part.':tries'};
                    $totalTries += $tries;

                    my $val = $cache->{$name.":$Version:$problem".
                                       ":resource.$part.solved"};
                    if    ($val eq 'correct_by_student')   {$code = 'C';} 
                    elsif ($val eq 'correct_by_override')  {$code = 'O';}
                    elsif ($val eq 'incorrect_attempted')  {$code = 'I';} 
                    elsif ($val eq 'incorrect_by_override'){$code = 'I';}
                    elsif ($val eq 'excused')              {$code = 'x';}
                    $partData{$part.':code'}=$code;

                    if($partData{$part.':wrong'} ne 0 && 
                       ($code eq 'C' || $code eq 'O')) {
                        $partData{$part.':wrong'}--;
                    }
                }
            }

            # Loop through all the parts for the current problem in the 
            # correct order and prepare the output
            foreach (split(/\:/,$cache->{$sequence.':'.$problemID.
                                         ':parts'})) {
                my $Yes = 0;
                if($partData{$_.':code'} eq 'C' || 
                   $partData{$_.':code'} eq 'O') {
                    $Yes=1;
                }
                #my $ptr = "$hash{'title_'.$ResId}";
                my $ptr = $tempProblemOrder.'&'.$problemID;

                if($_ > 1) {
                    $ptr .= "*(part $_)";
                    $Dis .= '&';
                }

		my ($pr_no,$dod)=split('&',$ptr);
		my $DoDiff=$DoDiff{$dod};
#               $r->print('<br>'.$name.'---'.$ptr.'==='.$DoDiff);

                my $Fac = ($partData{$_.':Tries'}) ? 
                    ($partData{$_.':awarded'}/$partData{$_.':tries'}) : 0;
                my $DisF;
                if($Fac > 0 &&  $Fac < 1) { 
                    $DisF = sprintf( "%.4f", $Fac );
                } else {
                    $DisF = $Fac;
                }

                if ($Discuss{"$name:$problem"}) {
		    $TotDiscuss++;
                    $Discussed=1;
                }
                my $time = $cache->{"$name:$LatestVersion:$problem:timestamp"};
                $Dis .= $tempProblemOrder.'='.$DisF.'+'.$Yes;
                $ptr .= '&'.$partData{$_.'.Tries'}.
                        '&'.$partData{$_.'.Wrongs'}.
                        '&'.$partData{$_.'.Code'};
                push (@$list, $ptr."&$Discussed");

####		if ($DoDiff>0.85) {

                $TimeTot += $time;

                if ($Yes==1 && $partData{$_.'.Tries'}==1) {
		    $TotFirst++;
                }
		my $Acts= $Activity{$name.':'.$problem};
		if ($Acts) {
		    my $Pt=&ProcAct( $Acts, $time );
		    #my ($spe,$beg) = split(/\+/,$Pt);
                    my $spe= $Pt;
		    if ($Yes==1) {$spent_yes += $spe;}
		    $spent += $spe;
		    #$Beg += $beg;
#                   $r->print('<br>'.$name.'---'.$problem.'---'.$spe);
		}
		$TotalOpend++;
		$ProbTot++;

                $tempProblemOrder++;
            }
        }
	my $pstr;
        if($totalTries) {
	    my $DisFac = ($totalAwarded/$totalTries);
	    my $DisFactor = sprintf( "%.4f", $DisFac );
            my $TS = sprintf( "%.2f", $spent );
            my $TS_yes = sprintf( "%.2f", $spent_yes );
	   # $DiscFac{$DisFactor}=$Dis;
	    $pstr=$DisFactor.':'.$name.':'.$ProbTot.':'.$TotalOpend.':'.
                  $totalTries.':'.$ProbSolved.':'.$TotFirst.':'.
                  $TS_yes.':'.$TS.':'.$TotDiscuss;
	    $discriminantFactor{$pstr}=$Dis;
	}
    }

    return (\%discriminantFactor);
}


=pod
sub MySort {          
    if ( $Pos > 0 ) {
	if ($ENV{'form.order'} eq 'Descending') {$b <=> $a;}
	else { $a <=> $b; }
    }
    else {
	if ($ENV{'form.order'} eq 'Descending') {$b cmp $a;}
	else { $a cmp $b; }
    }
}
=cut

sub BuildStatisticsTable {
    my ($cache,$discriminantFactor,$list,$headings,$students)=@_;

#6666666
#    my $file="/home/httpd/perl/tmp/183d.txt";
#    open(OUT, ">$file");
#6666666
    &Create_PrgWin();
##777777
##    &LoadActivityLog();
##    $r->print('<script>popwin.document.popremain.remaining.value="'.
##              'Loading Discussion...";</script>');
##    &LoadDoDiffFile();
    &LoadDiscussion();

    my $p_count = 0;
    my $nIndex = 0;
    my $dummy;
    my $p_val;
    my $ResId;
    my $NoElements = scalar @$list;

    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
        if($cache->{'ProblemStatisticsMap'} ne 'All Maps'  &&
           $cache->{'ProblemStatisticsMap'} ne $cache->{$sequence.':title'}) {
            next;
        }

	&CreateProblemStatisticsTableHeading($cache->{'DisplayFormat'},
                                             $cache->{$sequence.':source'}, 
                                             $cache->{$sequence.':title'},
                                             $headings);

##777777
##    &Classify($discriminantFactor, $students);


	my ($Hid,$pr)=split(/\:/,$mapsort{$_});
	my @lpr=split(/\&/,$pr);
	for (my $i=1; $i<=$#lpr; $i++) {
	    my %storestats=();
	    my ($PrOrd,$Prob,$Tries,$Wrongs,$Code,$Disc)=split(/\&/,$list->[$nIndex]);
	    my $Temp = $Prob;
	    my $MxTries = 0;
	    my $TotalTries = 0;
	    my $YES = 0;
	    my $Incorrect = 0;
	    my $Override = 0;
	    my $StdNo = 0;
	    my $DiscNo=0;
	    my @StdLst;
	    while ( $PrOrd == $lpr[$i] ) 
	    {
		$nIndex++;
		$StdNo++;
		$StdLst[ $StdNo ] = $Tries;
		$TotalTries += $Tries;
		if ( $MxTries < $Tries ) { $MxTries = $Tries; } 
		if ( $Code eq 'C' ){ $YES++; }
		elsif( $Code eq 'I' ) { $Incorrect++; }
		elsif( $Code eq 'O' ) { $Override++; }
		elsif( $Code eq 'U' ) { $StdNo--; }
		($PrOrd,$Prob,$Tries,$Wrongs,$Code,$Disc)=split(/\&/,$list->[$nIndex]);
	    }	

	    $p_count++;
	    my $Dummy;
	    ($ResId,$Dummy)=split(/\*/,$Temp);

	    $Temp = '<a href="'.$hash{'src_'.$ResId}.
                '" target="_blank">'.$hash{'title_'.$ResId}.$Dummy.'</a>';

	    my $res = &Apache::lonnet::declutter($hash{'src_'.$ResId});
	    my $urlres=$res;

	    $ResId=~/(\d+)\.(\d+)/;
	    my $Map = &Apache::lonnet::declutter( $hash{'map_id_'.$1} );
	    $urlres=$Map;
 
	    $res = '<a href="'.$hash{'src_'.$ResId}.'">'.$res.'</a>';
	    #$Map = '<a href="'.$Map.'">'.$res.'</a>';

#------------------------ Compute the Average of Tries about one problem
	    my $Average = ($StdNo) ? $TotalTries/$StdNo : 0;

	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___timestamp'}=time;       
	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___stdno'}=$StdNo;
	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___avetries'}=$Average;
   
#-------------------------------- Compute percentage of Wrong tries
	    my $Wrong = ( $StdNo ) ? 100 * ( $Incorrect / $StdNo ) : 0;

#-------------------------------- Compute Standard Deviation
	    my $StdDev = 0; 
	    if ( $StdNo > 1 ) {
		for ( my $n = 0; $n < $StdNo; $n++ ) {
		    my $Dif = $StdLst[ $n ]-$Average;
		    $StdDev += $Dif*$Dif;
		} 
		$StdDev /= ( $StdNo - 1 );
		$StdDev = sqrt( $StdDev );
	    }

#-------------------------------- Compute Degree of Difficulty
	    my $DoDiff = 0;
	    if( $TotalTries > 0 ) {
		$DoDiff = 1 - ( ( $YES + $Override ) / $TotalTries );
#	    $DoDiff =  ($TotalTries)/($YES + $Override+ 0.1);	    
	    }
       
	    $storestats{$ENV{'request.course.id'}.'___'.$urlres.'___difficulty'}=$DoDiff;

#-------------------------------- Compute the Skewness
	    my $Skewness = 0;
	    my $Sum = 0; 
	    if ( $StdNo > 0 && $StdDev > 0 ) {
		for ( my $n = 0; $n < $StdNo; $n++ ) {
		    my $Dif = $StdLst[ $n ]-$Average;
		    $Skewness += $Dif*$Dif*$Dif;
		} 
		$Skewness /= $StdNo;
		$Skewness /= $StdDev*$StdDev*$StdDev;
	    }

#--------------------- Compute the Discrimination Factors
            my ($Up1,$Up2)=split(/\:/,':');#jason$DisUp->{$lpr[$i]});
	    my ($Lw1,$Lw2)=split(/\:/,':');#jason$DisLow->{$lpr[$i]});
	    my $Dis1 = $Up1 - $Lw1;
	    my $Dis2 = $Up2 - $Lw2;
	    my $_D1 = sprintf("%.2f", $Dis1);
	    my $_D2 = sprintf("%.2f", $Dis2);

#-----------------  Some restition in presenting the float numbers
	    my $Avg = sprintf( "%.2f", $Average );
	    my $Wrng = sprintf( "%.1f", $Wrong );
	    my $SD = sprintf( "%.1f", $StdDev );
	    my $DoD = sprintf( "%.2f", $DoDiff );
	    my $Sk = sprintf( "%.1f", $Skewness );
	    my $join = $lpr[$i].'&'.$Temp.'&'.$StdNo.'&'.
                       $TotalTries.'&'.$MxTries.'&'.$Avg.'&'.
                       $YES.'&'.$Override.'&'.$Wrng.'&'.$DoD.'&'.
		       $SD.'&'.$Sk.'&'.$_D1.'&'.$_D2.'&'.
                       $DiscNo.'&'.$Prob;
	    $CachData{($p_count-1)}=$join;

#6666666
#	    $r->print('<br>'.$out.'&'.$DoD);
#            print (OUT $out.'@'.$DoD.'&');
#6666666

	    $urlres=~/^(\w+)\/(\w+)/;
	    if ($StdNo) { 
		&Apache::lonnet::put('resevaldata',\%storestats,$1,$2); 
	    }
#-------------------------------- Row of statistical table
            &TableRow($cache,$join,$i,($p_count-1));
	}
	&CloseTable($cache);
    }
    &Close_PrgWin();
#666666
#    close( OUT );
#666666
}

=pod
sub Cache_Statistics {
    my ($cache)=@_;
    my @list = ();
    my $Useful;
    my $UnUseful;
#    $r->print('<input type="hidden" name="show" value="excel" />'."\n"); 
    my %myHeader = reverse( %Header );
    $Pos = $myHeader{$ENV{'form.sort'}};
    if ($Pos > 0) {$Pos++;}
    my $p_count = 0;
    foreach my $key( keys %CachData) { 
	my @Temp=split(/\&/,$CachData{$key});
	if ( $Pos == 0 ) {
	    ($UnUseful,$Useful)=split(/\>/,$Temp[$Pos]);
	}
	else {
	    $Useful = $Temp[$Pos];
	}   
	$list[$p_count]=$Useful.'@'.$CachData{$key};
        $p_count++;
    }

    @list = sort MySort (@list);

    my $nIndex=0;

    if ( $Pos == 0 ) {
	foreach (sort keys %mapsort) {
	    my ($Hid,$pr)=split(/\:/,$mapsort{$_});
	    &CreateProblemStatisticsTableHeading($cache,1,$Hid);
	    my @lpr=split(/\&/,$pr);
	    for (my $i=1; $i<=$#lpr; $i++) {
		my($Pre, $Post) = split(/\@/,$list[$nIndex]); 
		#$r->print('<br>'.$Pre.'---'.$Post);
		&TableRow($cache,$Post,$i,$nIndex);
		$nIndex++;
	    }
	    &CloseTable($cache);
	}
    }
    else {
	&CreateProblemStatisticsTableHeading($cache,0);
	for ( my $nIndex = 0; $nIndex < $p_count; $nIndex++ ) {
	    my($Pre, $Post) = split(/\@/,$list[$nIndex]); 
	    &TableRow($cache,$Post,$nIndex,$nIndex);
	} 
	&CloseTable($cache);
    }
}
=cut 



sub TableRow {
    my ($Str,$Idx,$RealIdx)=@_;
    my($PrOrd,$Temp,$StdNo,$TotalTries,$MxTries,$Avg,$YES,$Override,
       $Wrng,$DoD,$SD,$Sk,$_D1,$_D2,$DiscNo,$Prob)=split(/\&/,$Str);	
    if ($ENV{'form.showcsv'}) {
        my ($ResId,$Dummy)=split(/\*/,$Prob);
        my $Ptr =  "\n".'<br>'.
               "\n".'"'.($RealIdx+1).'",'.
               "\n".'"'.$hash{'title_'.$ResId}.$Dummy.'",'.
               "\n".'"'.$hash{'src_'.$ResId}.'",'.
               "\n".'"'.$StdNo.'",'.
               "\n".'"'.$TotalTries.'",'.
               "\n".'"'.$MxTries.'",'.
               "\n".'"'.$Avg.'",'.
               "\n".'"'.$YES.'",'.
               "\n".'"'.$Override.'",'.
               "\n".'"'.$Wrng.'",'.
               "\n".'"'.$DoD.'",'.
               "\n".'"'.$SD.'",'.
               "\n".'"'.$Sk.'",'.
               "\n".'"'.$_D1.'",'.
	       "\n".'"'.$_D2.'"'.
	       "\n".'"'.$DiscNo.'"';

        $r->print("\n".$Ptr);
    }
    else{
        my $Ptr =  "\n".'<tr>'.
               "\n".'<td>'.($RealIdx+1).'</td>'.
          #     "\n".'<td>'.$PrOrd.$Temp.'</td>'.
               "\n".'<td>'.$Temp.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'> '.$StdNo.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'>'.$TotalTries.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'>'.$MxTries.'</td>'.
               "\n".'<td bgcolor='.$color{"gb"}.'>'.$Avg.'</td>'.
               "\n".'<td bgcolor='.$color{"gb"}.'> '.$YES.'</td>'.
               "\n".'<td bgcolor='.$color{"gb"}.'> '.$Override.'</td>'.
               "\n".'<td bgcolor='.$color{"red"}.'> '.$Wrng.'</td>'.
               "\n".'<td bgcolor='.$color{"red"}.'> '.$DoD.'</td>'.
               "\n".'<td bgcolor='.$color{"green"}.'> '.$SD.'</td>'.
               "\n".'<td bgcolor='.$color{"green"}.'> '.$Sk.'</td>'.
               "\n".'<td bgcolor='.$color{"purple"}.'> '.$_D1.'</td>'.
	       "\n".'<td bgcolor='.$color{"purple"}.'> '.$_D2.'</td>'.
               "\n".'<td bgcolor='.$color{"yellow"}.'> '.$DiscNo.'</td>';
        $r->print("\n".$Ptr.'</tr>' );
    }
    $GraphDat{$RealIdx}=$DoD.':'.$Wrng;
}

sub StatusOptions {
    my ($cache)=@_;

    my $Status = $cache->{'Status'};
    my $OpSel1 = '';
    my $OpSel2 = '';
    my $OpSel3 = '';

    if($Status eq 'Any')         { $OpSel3 = ' selected'; }
    elsif($Status eq 'Expired' ) { $OpSel2 = ' selected'; }
    else                         { $OpSel1 = ' selected'; }

    my $Ptr = '';
    $Ptr .= '<tr><td align="right"><b>Student Status:</b></td>'."\n";
    $Ptr .= '<td align="left"><select name="Status">';
    $Ptr .= '<option'.$OpSel1.'>Active</option>'."\n";
    $Ptr .= '<option'.$OpSel2.'>Expired</option>'."\n";
    $Ptr .= '<option'.$OpSel3.'>Any</option>'."\n";
    $Ptr .= '</select></td></tr>'."\n";

    return $Ptr;
}

sub AscendOrderOptions {
    my ($cache)=@_;

    my $order = $cache->{'Ascend'};
    my $OpSel1 = '';
    my $OpSel2 = '';

    if($order eq 'Ascending') {
        $OpSel1 = ' selected';
    } else {
        $OpSel2 = ' selected';
    }

    my $Ptr = '';
    $Ptr .= '<tr><td align="right"><b>Sorting Type:</b></td>'."\n";
    $Ptr .= '<td align="left"><select name="Ascend">'."\n";
    $Ptr .= '<option'.$OpSel1.'>Ascending</option>'."\n".
	    '<option'.$OpSel2.'>Descending</option>'."\n";
    $Ptr .= '</select></td></tr>'."\n";

    return $Ptr;
}

sub ProblemStatisticsButtons {
    my ($cache)=@_;

    my $Ptr = '<tr><td></td><td align="left">';
    $Ptr .= '<input type=submit name="ProblemStatisticsRecalculate" ';
    $Ptr .= 'value="Recalculate Statistics"/>'."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="DoDiffGraph" ';
    $Ptr .= 'value="DoDiff Graph" />'."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="PercentWrongGraph" ';
    $Ptr .= 'value="%Wrong Graph" />'."\n";
    $Ptr .= '&nbsp;&nbsp;&nbsp;';
    $Ptr .= '<input type="submit" name="DisplayCSVFormat" ';
    if($cache->{'DisplayFormat'} eq 'Display CSV Format') {
        $Ptr .= 'value="Display CSV Format" />'."\n";
    } else {
        $Ptr .= 'value="Display Table Format" />'."\n";
    }
    $Ptr .= '</td></tr>';

    return $Ptr;
}

sub ProblemStatisticsLegend {
    my $Ptr = '';
    $Ptr = '<table border="0">';
    $Ptr .= '<tr><td>';
    $Ptr .= '<b>#Stdnts</b>:</td>';
    $Ptr .= '<td>Total Number of Students opened the problem.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Tries</b>:</td>';
    $Ptr .= '<td>Total Number of Tries for solving the problem.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Mod</b>:</td>';
    $Ptr .= '<td>Maximunm Number of Tries for solving the problem.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Mean</b>:</td>';
    $Ptr .= '<td>Average Number of the tries. [ Tries / #Stdnts ]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>#YES</b>:</td>';
    $Ptr .= '<td>Number of students solved the problem correctly.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>#yes</b>:</td>';
    $Ptr .= '<td>Number of students solved the problem by override.';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>%Wrng</b>:</td>';
    $Ptr .= '<td>Percentage of students tried to solve the problem ';
    $Ptr .= 'but still incorrect. [ 100*((#Stdnts-(#YES+#yes))/#Stdnts) ]';
    $Ptr .= '</td></tr><tr><td>';
#    Kashy formula
#    '<b>  DoDiff </b>: Degree of Difficulty of the problem.<br>'.
#    '[ Tries/(#YES+#yes+0.1) ]<br>'.
    #Gerd formula
    $Ptr .= '<b>DoDiff</b>:</td>';
    $Ptr .= '<td>Degree of Difficulty of the problem.  ';
    $Ptr .= '[ 1 - ((#YES+#yes) / Tries) ]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>S.D.</b>:</td>';
    $Ptr .= '<td>Standard Deviation of the tries.  ';
    $Ptr .= '[ sqrt(sum((Xi - Mean)^2)) / (#Stdnts-1) ';
    $Ptr .= 'where Xi denotes every student\'s tries ]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Skew.</b>:</td>';
    $Ptr .= '<td>Skewness of the students tries.';
    $Ptr .= '[(sqrt( sum((Xi - Mean)^3) / #Stdnts)) / (S.D.^3)]';
    $Ptr .= '</td></tr><tr><td>';
    $Ptr .= '<b>Dis.F.</b>:</td>';
    $Ptr .= '<td>Discrimination Factor: A Standard for evaluating the ';
    $Ptr .= 'problem according to a Criterion<br>';
    $Ptr .= '<b>[Applied Criterion in %27 Upper Students - ';
    $Ptr .= 'Applied the same Criterion in %27 Lower Students]</b><br>';
    $Ptr .= '<b>1st Criterion</b> for Sorting the Students: ';
    $Ptr .= '<b>Sum of Partial Credit Awarded / Total Number of Tries</b><br>';
    $Ptr .= '<b>2nd Criterion</b> for Sorting the Students: ';
    $Ptr .= '<b>Total number of Correct Answers / Total Number of Tries</b>';
    $Ptr .= '</td></tr>';
    $Ptr .= '<tr><td><b>Disc.</b></td>';
    $Ptr .= '<td>Number of Students had at least one discussion.';
    $Ptr .= '</td></tr></table>';

    return $Ptr;
}

#---- END Problem Statistics Web Page ----------------------------------------

#---- Problem Statistics Graph Web Page --------------------------------------

# ------------------------------------------- Prepare data for Graphical chart

sub GetGraphData {
    my $ylab = shift;
    my $Col;
    my $data='';
    my $count = 0;
    my $Max = 0;
    my $cid=$ENV{'request.course.id'};
    my $GraphDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
                  "_$ENV{'user.domain'}_$cid\_graph.db";
    foreach (keys %GraphDat) {delete $GraphDat{$_};}
    if (-e "$GraphDB") {
	if (tie(%GraphDat,'GDBM_File',"$GraphDB",&GDBM_READER,0640)) {
	    if ( $ylab eq 'DoDiff Graph' ) {
		$ylab = 'Degree-of-Difficulty';
		$Col = 0;
	    }
	    else {
		$ylab = 'Wrong-Percentage';
		$Col = 1;
	    }
	    foreach (sort NumericSort keys %GraphDat) { 
		my @Temp=split(/\:/,$GraphDat{$_});
                my $inf = $Temp[$Col]; 
		if ( $Max < $inf ) {$Max = $inf;}
		$data .= $inf.',';
		$count++;
	    }
	    if ( $Max > 1 ) { 
		$Max += (10 - $Max % 10);
		$Max = int($Max);
	    }
	    else { $Max = 1; }
            untie(%GraphDat);
	    my $Course = $ENV{'course.'.$cid.'.description'};
	    $Course =~ s/\ /"_"/eg;
	    $GData=$Course.'&'.'Problems'.'&'.$ylab.'&'.$Max.'&'.$count.'&'.$data;
	}
	else {
	    $r->print("Unable to tie hash to db file");
	}
    }
}
#---- Problem Analysis Web Page ----------------------------------------------

sub IntervalOptions {
    my ($cache)=@_;

    my $interval = 1;
    for(my $n=1; $n<=7; $n++) {
        if($cache->{'Interval'} == $n) {
            $interval = $n;
        }
    }

    my $Ptr = '<br><b>Select number of intervals</b>'."\n".
       	      '<select name="Interval">'."\n";
    for(my $n=1; $n<=7;$ n++) {
	$Ptr .= '<option';
        if($interval == $n) {
            $Ptr .= ' selected';
        }
	$Ptr .= '>'.$n."</option>"."\n";
    }
    $Ptr .= '</select>'."\n";

    return $Ptr;
}

sub OptionResponseTable {
    my ($cache)=@_;
    my $Str = '';
    $Str .= '<br><b> Option Response Problems in this course:</b>'."\n";
    $Str .= '<br><br>'."\n";
    $Str .= "<table border=2><tr><th> \# </th><th> Problem Title </th>";
    $Str .= '<th> Resource </th><th> Analysis  </th></tr>'."\n";

    my $number=1;
    foreach (split(':::',$cache->{'OptionResponses'})) {
        my ($uri,$title,$part,$problem)=split('::',$_);
        my $Temp = '<a href="'.$uri.'" target="_blank">'.$title.'</a>';
        $Str .= '<tr>';
        $Str .= '<td> '.$number.' </td>';
        $Str .= '<td bgcolor="'.$color{"green"}.'"> '.$Temp.' </td>';
        $Str .= '<td bgcolor="'.$color{"yellow"}.'"> '.$uri.' </td>';
        $Str .= '<td><input type="submit" name="Analyze:::'.$uri.':::';
        $Str .= $title.':::'.$part.':::'.$problem.'" value="';
        $Str .= 'Analyze" /></td></tr>'."\n";
        $number++;
    }
    $Str .= '</table>'."\n";

    return $Str;
}

#---- END Problem Analysis Web Page ------------------------------------------

#---- Student Assessment Web Page --------------------------------------------

# ------ Create different Student Report 
sub StudentReport {
    my ($cache, $name)=@_;

    my $Str = '';
    if($cache->{$name.':error'} =~ /course/) {
        my ($username)=split(':',$name);
        $Str .= '<b><font color="blue">No course data for student </font>';
        $Str .= '<font color="red">'.$username.'.</font></b><br>';
        return $Str;
    }

    $Str .= "<table border=2><tr><th> \# </th><th> Set Title </th>";
    $Str .= '<th> Results </th><th> Tries </th></tr>'."\n";

    my $codes;
    my $attempts;
    foreach my $sequence (split(':', $cache->{'orderedSequences'})) {
        if($cache->{'StudentAssessmentMap'} ne 'All Maps'  &&
           $cache->{'StudentAssessmentMap'} ne $cache->{$sequence.':title'}) {
            next;
        }

        $Str .= '<tr><td>'.$sequence.'</td>';
        $Str .= '<td>'.$cache->{$sequence.':title'}.'</td>';

        $codes = '';
        $attempts = '';
        foreach my $problemID (split(':', $cache->{$sequence.':problems'})) {
            my $problem = $cache->{$problemID.':problem'};
            my $LatestVersion = $cache->{$name.':version:'.$problem};

            # Output dashes for all the parts of this problem if there
            # is no version information about the current problem.
            if(!$LatestVersion) {
                foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                      $problemID.
                                                      ':parts'})) {
		    $codes    .= "-,";
                    $attempts .= "0,"; 
                }
                next;
            }

            my %partData=undef;
            # Initialize part data, display skips correctly
            # Skip refers to when a student made no submissions on that
            # part/problem.
            foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                  $problemID.
                                                  ':parts'})) {
                $partData{$part.':tries'}=0;
                $partData{$part.':code'}='-';
            }

            # Looping through all the versions of each part, starting with the
            # oldest version.  Basically, it gets the most recent 
            # set of grade data for each part.
	    for(my $Version=1; $Version<=$LatestVersion; $Version++) {
                foreach my $part (split(/\:/,$cache->{$sequence.':'.
                                                      $problemID.
                                                      ':parts'})) {

                    if(!defined($cache->{$name.":$Version:$problem".
                                               ":resource.$part.solved"})) {
                        # No grade for this submission, so skip
                        next;
                    }

                    my $tries=0;
                    my $code='U';

                    $tries = $cache->{$name.":$Version:$problem".
                                      ":resource.$part.tries"};
                    $partData{$part.':tries'}=($tries) ? $tries : 0;

                    my $val = $cache->{$name.":$Version:$problem".
                                       ":resource.$part.solved"};
                    if    ($val eq 'correct_by_student')   {$code = 'Y';} 
                    elsif ($val eq 'correct_by_override')  {$code = 'y';}
                    elsif ($val eq 'incorrect_attempted')  {$code = 'N';} 
                    elsif ($val eq 'incorrect_by_override'){$code = 'N';}
                    elsif ($val eq 'excused')              {$code = 'x';}
                    $partData{$part.':code'}=$code;
                }
            }

            # Loop through all the parts for the current problem in the 
            # correct order and prepare the output
            foreach (split(/\:/,$cache->{$sequence.':'.$problemID.
                                         ':parts'})) {
                $codes    .= $partData{$_.':code'}.',';
                $attempts .= $partData{$_.':tries'}.','; 
            }
        }
        $codes    =~ s/,$//;
        $attempts =~ s/,$//;
        $Str .= '<td>'.$codes.'</td>';
        $Str .= '<td>'.$attempts.'</td>';
        $Str .= '</tr>'."\n";
    }

    $Str .= '</table>'."\n";

    return $Str;
}

#---- END Student Assessment Web Page ----------------------------------------

#---- Menu Web Page ----------------------------------------------------------

#---- END Menu Web Page ------------------------------------------------------

#---- HELPER FUNCTIONS -------------------------------------------------------

sub CheckFormElement {
    my ($cache, $ENVName, $cacheName, $default)=@_;

    if(defined($ENV{'form.'.$ENVName})) {
        $cache->{$cacheName} = $ENV{'form.'.$ENVName};
    } elsif(!defined($cache->{$cacheName})) {
        $cache->{$cacheName} = $default;
    }

    return;
}

sub ProcessFormData{
    my ($cache)=@_;

    $cache->{'reportKey'} = 'false';

    &Apache::loncommon::get_unprocessed_cgi($ENV{'QUERY_STRING'},
                                            ['sort','download']);
    &CheckFormElement($cache, 'Status', 'Status', 'Active');
    &CheckFormElement($cache, 'postdata', 'reportSelected', 'Class list');
    &CheckFormElement($cache, 'reportSelected', 'reportSelected', 
                      'Class list');
    &CheckFormElement($cache, 'DownloadAll', 'DownloadAll', 'false');
    &CheckFormElement($cache, 'sort', 'sort', 'fullname');
    &CheckFormElement($cache, 'download', 'download', 'false');

    if(defined($ENV{'form.CreateStudentAssessment'}) ||
       defined($ENV{'form.NextStudent'}) ||
       defined($ENV{'form.PreviousStudent'})) {
        $cache->{'reportSelected'} = 'Student Assessment';
    }
    if(defined($ENV{'form.NextStudent'})) {
        $cache->{'StudentAssessmentMove'} = 'next';
    } elsif(defined($ENV{'form.PreviousStudent'})) {
        $cache->{'StudentAssessmentMove'} = 'previous';
    } else {
        $cache->{'StudentAssessmentMove'} = 'selected';
    }
    &CheckFormElement($cache, 'StudentAssessmentMap', 'StudentAssessmentMap', 
                      'All Maps');
    &CheckFormElement($cache, 'StudentAssessmentStudent', 
                      'StudentAssessmentStudent', 'No Student Selected');

    foreach (keys(%ENV)) {
        if(/form\.Analyze:::/) {
#            $cache->{'reportSelected'} = 'Analyze';
#            $cache->{'reportKey'} = 'Problem Analysis';
            my ($uri, $title, $part, $problem);
            (undef, $uri, $title, $part, $problem)=split(':::', $_);
            $cache->{'AnalyzeURI'}     = $uri;
            $cache->{'AnalyzeTitle'}   = $title;
            $cache->{'AnalyzePart'}    = $part;
            $cache->{'AnalyzeProblem'} = $problem;
            
            &CheckFormElement($cache, 'Interval', 'Interval', '1');
        }
    }

    return;

    # Select page to display
    if(defined($ENV{'form.ProblemStatistics'}) ||
       defined($ENV{'form.ProblemStatisticsRecalculate'}) || 
       defined($ENV{'form.DisplayCSVFormat'})) {
        $cache->{'GoToPage'} = 'ProblemStatistics';
        &CheckFormElement($cache, 'DisplayCSVFormat',
                          'DisplayFormat', 'Display Table Format');
        &CheckFormElement($cache, 'Ascend','ProblemStatisticsAscend',
                          'Ascending');
        &CheckFormElement($cache, 'Maps', 'ProblemStatisticsMap', 
                          'All Maps');
    } elsif(defined($ENV{'form.ProblemAnalysis'})) {
        $cache->{'GoToPage'} = 'ProblemAnalysis';
        &CheckFormElement($cache, 'Interval', 'Interval', '1');
    } elsif(defined($ENV{'form.DoDiffGraph'})) {
        $cache->{'GoToPage'} = 'DoDiffGraph';
    } elsif(defined($ENV{'form.PercentWrongGraph'})) {
        $cache->{'GoToPage'} = 'PercentWrongGraph';
    } elsif(defined($ENV{'form.ActivityLog'})) {
        $cache->{'GoToPage'} = 'ActivityLog';
    } else {
        $cache->{'GoToPage'} = 'Menu';
    }

    &CheckFormElement($cache, 'Status', 'Status', 'Active');

    return;
}

=pod

=item &SortStudents()

Determines which students to display and in which order.  Which are 
displayed are determined by their status(active/expired).  The order
is determined by the sort button pressed (default to username).  The
type of sorting is username, lastname, or section.

=over 4

Input: $students, $CacheData

$students: A array pointer to a list of students (username:domain)

$CacheData: A pointer to the hash tied to the cached data

Output: \@order

@order: An ordered list of students (username:domain)

=back

=cut

sub SortStudents {
    my ($cache)=@_;

    my @students = split(':::',$cache->{'NamesOfStudents'});
    my @sorted1Students=();
    foreach (@students) {
        if($cache->{'Status'} eq 'Any' || 
           $cache->{$_.':Status'} eq $cache->{'Status'}) {
            push(@sorted1Students, $_);
        }
    }

    my $sortBy = '';
    if(defined($cache->{'sort'})) {
        $sortBy = ':'.$cache->{'sort'};
    }
    my @order = sort { $cache->{$a.$sortBy} cmp $cache->{$b.$sortBy} ||
                       $cache->{$a.':fullname'} cmp $cache->{$b.':fullname'} } 
                @sorted1Students;

    return \@order;
}

sub PrepareData {
    my ($c, $cacheDB)=@_;

    # Test for access to the cache data
    my $courseID=$ENV{'request.course.id'};
    my $isRecalculate=0;
    if(defined($ENV{'form.Recalculate'})) {
        $isRecalculate=1;
    }

    my $isCached = &Apache::loncoursedata::TestCacheData($cacheDB, 
                                                         $isRecalculate);
    if($isCached < 0) {
        return "Unable to tie hash to db file.";
    }

    # Download class list information if not using cached data
    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT,0640)) {
        return "Unable to tie hash to db file.";
    }

    if(!$isCached) {
        my $processTopResourceMapReturn=
            &Apache::loncoursedata::ProcessTopResourceMap(\%cache, $c);
        if($processTopResourceMapReturn ne 'OK') {
            untie(%cache);
            return $processTopResourceMapReturn;
        }
    }

    if($c->aborted()) {
        untie(%cache);
        return 'aborted'; 
    }

    my $classlist=&Apache::loncoursedata::DownloadClasslist($courseID,
                                                $cache{'ClasslistTimestamp'},
                                                $c);
    foreach (keys(%$classlist)) {
        if(/^(con_lost|error|no_such_host)/i) {
            untie(%cache);
            return "Error getting student data.";
        }
    }

    if($c->aborted()) {
        untie(%cache);
        return 'aborted'; 
    }

    # Active is a temporary solution, remember to change
    Apache::loncoursedata::ProcessClasslist(\%cache,$classlist,$courseID,$c);
    if($c->aborted()) {
        untie(%cache);
        return 'aborted'; 
    }

    &ProcessFormData(\%cache);
    my $students = &SortStudents(\%cache);

    if($cache{'download'} ne 'false') {
        my $who = $cache{'download'};
        my $courseData = 
            &Apache::loncoursedata::DownloadStudentCourseInformation(
                                             $who, $courseID, 
                                             $cache{$who.':lastDownloadTime'});
        &Apache::loncoursedata::ProcessStudentData(\%cache, $courseData, $who);
        $cache{'download'} = 'false';
    } elsif($cache{'DownloadAll'} ne 'false') {
        my @allStudents;
        if($cache{'DownloadAll'} eq 'sorted') {
            @allStudents = @$students;
        } else {
            @allStudents = split(':::', $cache{'NamesOfStudents'});
        }
        foreach (@allStudents) {
            my $courseData = 
                &Apache::loncoursedata::DownloadStudentCourseInformation(
                                             $_, $courseID, 
                                             $cache{$_.':lastDownloadTime'});
            &Apache::loncoursedata::ProcessStudentData(\%cache, $courseData, 
                                                       $_);
            if($c->aborted()) {
                untie(%cache);
                return 'aborted'; 
            }
        }
        $cache{'DownloadAll'} = 'false';
    }

    if($c->aborted()) {
        untie(%cache);
        return 'aborted'; 
    }

    if($c->aborted()) {
        untie(%cache);
        return 'aborted'; 
    }

    untie(%cache);

    return ('OK', $students);
}

# Create progress
sub Create_PrgWin {
    $r->print(<<ENDPOP);
    <script>
    popwin=open('','popwin','width=400,height=100');
    popwin.document.writeln('<html><body bgcolor="#88DDFF">'+
      '<title>LON-CAPA Statistics</title>'+
      '<h4>Computation Progress</h4>'+
      '<form name=popremain>'+
      '<input type=text size=35 name=remaining value=Starting></form>'+
      '</body></html>');
    popwin.document.close();
    </script>
ENDPOP

    $r->rflush();
}

# update progress
sub Update_PrgWin {
    my ($totalStudents,$index,$name)=@_;
    $r->print('<script>popwin.document.popremain.remaining.value="'.
              'Computing '.$index.'/'.$totalStudents.': '.
              $name.'";</script>');
    $r->rflush();
}

# close Progress Line
sub Close_PrgWin {
    $r->print('<script>popwin.close()</script>');
    $r->rflush(); 
}

# For loading the colored table for display or un-colored for print
sub setbgcolor {
    my $PrintTable=shift;
    undef %color;
    if ($PrintTable){
	$color{"gb"}="#FFFFFF";
	$color{"red"}="#FFFFFF";
	$color{"yellow"}="#FFFFFF";
	$color{"green"}="#FFFFFF";
	$color{"purple"}="#FFFFFF";
    } else {
	$color{"gb"}="#DDFFFF";
	$color{"red"}="#FFDDDD";
	$color{"yellow"}="#EEFFCC";
	$color{"green"}="#DDFFDD";
	$color{"purple"}="#FFDDFF";
    }

    return;
}

sub initial {
    undef %hash;
    undef %CachData;
    undef %GraphDat;
    undef %ConceptData;
    undef $GData;
}

#---- END HELPER FUNCTIONS ---------------------------------------------------

sub BuildProblemStatisticsPage {
    my ($cacheDB, $students, $courseID, $c)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    my $Ptr = '';
    $Ptr .= '<table border="0"><tbody>';
    $Ptr .= '<tr><td align="right"><b>Select Map</b></td>'."\n";
    $Ptr .= '<td align="left">';
    $Ptr .= &Apache::lonhtmlcommon::MapOptions(\%cache, 'ProblemStatistics');
    $Ptr .= '</td></tr>'."\n";
    $r->print($Ptr);
    $r->print(&AscendOrderOptions());
    $r->print(&ProblemStatisticsButtons(\%cache));
    $r->print('</table>');

    $r->print(&ProblemStatisticsLegend());

    untie(%cache);
    foreach (@$students) {
        my $courseData = 
            &Apache::loncoursedata::DownloadStudentCourseInformation($_, 
                                                                    $courseID);
        last if ($c->aborted());
        if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT,0640)) {
            &Apache::loncoursedata::ProcessStudentData(\%cache, 
                                                       $courseData, $_);
            untie(%cache);
        }
    }
    if($c->aborted()) { return; }

    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }
    my $discriminantFactor;
    my @list=();
    foreach (@$students) {
        $discriminantFactor = &ExtractStudentData(\%cache, $_, \@list);
    }

    my ($upper, $lower) = &Discriminant($discriminantFactor);
    my %Header = (0,"Homework Sets Order",1,"#Stdnts",2,"Tries",3,"Mod",
                  4,"Mean",5,"#YES",6,"#yes",7,"%Wrng",8,"DoDiff",
                  9,"S.D.",10,"Skew.",11,"D.F.1st",12,"D.F.2nd", 13, "Disc.");
    &BuildStatisticsTable(\%cache, $discriminantFactor, \@list, \%Header, 
                           $students);

    untie(%cache);

    return;
}

sub BuildDiffGraph {
    my ($courseID)=@_;

    my $graphData = &GetGraphData('DiffGraph', $courseID);
    $r->print('<IMG src="/cgi-bin/graph.gif?'.$graphData.'" />');

    return;
}

sub BuildWrongGraph {
    my ($courseID)=@_;

    my $graphData = &GetGraphData('WrongGraph', $courseID);
    $r->print('<IMG src="/cgi-bin/graph.gif?'.$graphData.'" />');

    return;
}

sub BuildAnalyzePage {
    my ($cacheDB, $students, $courseID)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    &ShowOpGraph(\%cache, $students, $courseID);

    untie(%cache);

    return;
}

sub BuildProblemAnalysisPage {
    my ($cacheDB)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    $r->print(&IntervalOptions());
    $r->print(&OptionResponseTable(\%cache));

    untie(%cache);

    return;
}

sub BuildStudentAssessmentPage {
    my ($cacheDB, $students, $courseID, $c)=@_;

    my %cache;

    my $Ptr = '';
    $Ptr .= '<table border="0"><tbody>';
    $r->print($Ptr);

    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return;
    }

    my $selectedName = $cache{'StudentAssessmentStudent'};
    for(my $index=0; 
        ($selectedName ne 'All Students') && ($index<(scalar @$students)); 
        $index++) {
        my $fullname = $cache{$students->[$index].':fullname'};
        if($fullname eq $selectedName) {
            if($cache{'StudentAssessmentMove'} eq 'next') {
                if($index == ((scalar @$students) - 1)) {
                    $selectedName = $students->[0];
                } else {
                    $selectedName = $students->[$index+1];
                }
            } elsif($cache{'StudentAssessmentMove'} eq 'previous') {
                if($index == 0) {
                    $selectedName = $students->[-1];
                } else {
                    $selectedName = $students->[$index-1];
                }
            } else {
                $selectedName = $students->[$index];
            }
            last;
        }
    }

    $Ptr .= '<tr><td align="right"><b>Select Map</b></td>'."\n";
    $Ptr .= '<td align="left">';
    $Ptr .= &Apache::lonhtmlcommon::MapOptions(\%cache, 'StudentAssessment');
    $Ptr .= '</td></tr>'."\n";
    $Ptr .= '<tr><td align="right"><b>Select Student</b></td>'."\n";
    $Ptr .= '<td align="left">'."\n";
    $Ptr .= &Apache::lonhtmlcommon::StudentOptions(\%cache, $students, 
                                                   $selectedName, 
                                                   'StudentAssessment');
    $Ptr .= '</td></tr>'."\n";
    untie(%cache);

    $Ptr .= '<tr><td></td><td align="left">';
    $Ptr .= '<input type="submit" name="CreateStudentAssessment" ';
    $Ptr .= 'value="Create Student Report" />';
    $Ptr .= '&nbsp&nbsp&nbsp';
    $Ptr .= '<input type="submit" name="PreviousStudent" ';
    $Ptr .= 'value="Previous Student" />';
    $Ptr .= '&nbsp&nbsp&nbsp';
    $Ptr .= '<input type="submit" name="NextStudent" ';
    $Ptr .= 'value="Next Student" />';
    $Ptr .= '&nbsp&nbsp&nbsp';
    $Ptr .= '</td></tr></tbody></table>'."\n";
    $r->print($Ptr);

    if($selectedName eq 'No Student Selected') {
	$r->print('<h3><font color=blue>WARNING: ');
        $r->print('Please select a student</font></h3>');
        return;
    }

    my $selected=0;
    foreach (@$students) {
        next if ($_ ne $selectedName && 
                 $selectedName ne 'All Students');
        $selected = 1;
        my $courseData = 
            &Apache::loncoursedata::DownloadStudentCourseInformation($_, 
                                                                    $courseID);
        last if ($c->aborted());
        if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_WRCREAT,0640)) {
            &Apache::loncoursedata::ProcessStudentData(\%cache, 
                                                       $courseData, $_);
            if(!$c->aborted()) { $r->print(&StudentReport(\%cache, $_)); }
            untie(%cache);
        }
    }
    if($selected == 0) {
	$r->print('<h3><font color=blue>WARNING: ');
        $r->print('Please select a student</font></h3>');
        return;
    }

    return;
}

sub BuildClasslist {
    my ($cacheDB,$students,$studentInformation,$headings,$spacePadding)=@_;

    my %cache;
    unless(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        return '<html><body>Unable to tie database.</body></html>';
    }

    my $Str='';
    $Str .= '<table border="0"><tr><td bgcolor="#777777">'."\n";
    $Str .= '<table border="0" cellpadding="3"><tr bgcolor="#e6ffff">'."\n";

    my $displayString = '<td align="left"><a href="/adm/statistics?';
    $displayString .= 'sort=LINKDATA">DISPLAYDATA&nbsp</a></td>'."\n";
    $Str .= &Apache::lonhtmlcommon::CreateStudentInformationHeadings(\%cache,
                                                           $studentInformation,
                                                           $headings,
                                                           $displayString);
    $Str .= '<td align="left">';
    $Str .= '<a href="/adm/statistics?sort=lastDownloadTime">';
    $Str .= 'Last Updated&nbsp&nbsp</a></td>'."\n";
    $Str .= '</tr>'."\n";
    my $alternate=0;
    foreach (@$students) {
        my ($username, $domain) = split(':', $_);
        if($alternate) {
            $Str .= '<tr bgcolor="#ffffe6"><td>';
        } else {
            $Str .= '<tr bgcolor="#ffffc6"><td>';
        }
        $alternate = ($alternate + 1) % 2;
        foreach my $data (@$studentInformation) {
            if($data eq 'fullname') {
                $Str .= '<a href="/adm/statistics?reportSelected=';
                $Str .= &Apache::lonnet::escape('Student Assessment').'">';
            }

            $Str .= $cache{$_.':'.$data}.'&nbsp';

            if($data eq 'fullname') {
                $Str .= '</a>';
            }

            $Str .= '</td><td>';
        }

        $Str .= '<a href="/adm/statistics?download='.$_.'">';
        my $downloadTime = $cache{$_.':lastDownloadTime'};
        if($downloadTime ne 'Not downloaded') {
            $downloadTime = localtime($downloadTime);
        }
        $Str .= $downloadTime;

        $Str .= '&nbsp</a></td></tr>'."\n";
    }

    $Str .= '</table></td></tr></table>'."\n";

    untie(%cache);

    return $Str;
}

sub BuildStatistics {
    my ($r)=@_;

    my $c = $r->connection;
    my @studentInformation=('fullname','section','id','domain','username');
    my @headings=('Full Name', 'Section', 'PID', 'Domain', 'User Name');
    my $spacePadding = '   ';
    my %reports = ('classlist'          => 'Class list',
                   'problem_statistics' => 'Problem Statistics',
                   'student_assessment' => 'Student Assessment',
                   'reportSelected'     => 'Class list');

    my %cache;
    my $courseID=$ENV{'request.course.id'};
    my $cacheDB = "/home/httpd/perl/tmp/$ENV{'user.name'}".
                  "_$ENV{'user.domain'}_$courseID\_statistics.db";

    &setbgcolor(0);
    my ($returnValue, $students) = &PrepareData($c, $cacheDB);
    if($returnValue ne 'OK') {
        $r->print('<html><body>'.$returnValue."\n".'</body></html>');
        return OK;
    }

    my $GoToPage;
    if(tie(%cache,'GDBM_File',$cacheDB,&GDBM_READER,0640)) {
        $GoToPage = $cache{'reportSelected'};
        $reports{'reportSelected'} = $cache{'reportSelected'};
#        if(defined($cache{'reportKey'}) && $cache{'reportKey'} ne 'false') {
#            $reports{$cache{'reportKey'}} = $cache{'reportSelected'};
#        }

        if(defined($cache{'OptionResponses'})) {
            $reports{'problem_analysis'} = 'Problem Analysis';
        }

        $r->print(&Apache::lonhtmlcommon::Title('LON-CAPA Statistics'));
        $r->print('<form name="Statistics" ');
        $r->print('method="post" action="/adm/statistics">');
        $r->print(&Apache::lonhtmlcommon::CreateStatisticsMainMenu(
                                                             $cache{'Status'}, 
                                                             \%reports));
        untie(%cache);
    } else {
        $r->print('<html><body>Unable to tie database.</body></html>');
        return OK;
    }

    if($GoToPage eq 'Activity Log') {
        &Activity();
    } elsif($GoToPage eq 'Problem Statistics') {
        &BuildProblemStatisticsPage($cacheDB, $students, $courseID, $c);
    } elsif($GoToPage eq 'Problem Analysis') {
        &BuildProblemAnalysisPage($cacheDB);
    } elsif($GoToPage eq 'Student Assessment') {
        &BuildStudentAssessmentPage($cacheDB, $students, $courseID, $c);
    } elsif($GoToPage eq 'Analyze') {
        &BuildAnalyzePage($cacheDB, $students, $courseID);
    } elsif($GoToPage eq 'DoDiffGraph') {
        &BuildDiffGraph($courseID);
    } elsif($GoToPage eq 'PercentWrongGraph') {
        &BuildWrongGraph($courseID);
    } elsif($GoToPage eq 'Class list') {
        $r->print(&BuildClasslist($cacheDB, $students, \@studentInformation,
                                  \@headings, $spacePadding));
    }

    $r->print('</form>'."\n");
    $r->print("\n".'</body>'."\n".'</html>');
    $r->rflush();

    return OK;
}

# ================================================================ Main Handler

sub handler {
    $r=shift;
    &initial();

    unless(&Apache::lonnet::allowed('vgr',$ENV{'request.course.id'})) {
        $ENV{'user.error.msg'}=
        $r->uri.":vgr:0:0:Cannot view grades for complete course";
        return HTTP_NOT_ACCEPTABLE; 
    }

    # Set document type for header only
    if($r->header_only) {
        if ($ENV{'browser.mathml'}) {
            $r->content_type('text/xml');
        } else {
            $r->content_type('text/html');
        }
        &Apache::loncommon::no_cache($r);
        $r->send_http_header;
        return OK;
    }

    unless($ENV{'request.course.fn'}) {
	my $requrl=$r->uri;
        $ENV{'user.error.msg'}="$requrl:bre:0:0:Course not initialized";
        return HTTP_NOT_ACCEPTABLE; 
    }

    $r->content_type('text/html');
    $r->send_http_header;

    &BuildStatistics($r);

    return OK;
}
1;
__END__

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