--- loncom/interface/statistics/lonproblemanalysis.pm	2003/10/10 13:35:43	1.29
+++ loncom/interface/statistics/lonproblemanalysis.pm	2003/10/20 20:42:39	1.43
@@ -1,6 +1,6 @@
 # The LearningOnline Network with CAPA
 #
-# $Id: lonproblemanalysis.pm,v 1.29 2003/10/10 13:35:43 matthew Exp $
+# $Id: lonproblemanalysis.pm,v 1.43 2003/10/20 20:42:39 matthew Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -34,6 +34,14 @@ use Apache::lonhtmlcommon();
 use Apache::loncoursedata();
 use Apache::lonstatistics;
 use Apache::lonlocal;
+use HTML::Entities();
+use Time::Local();
+use Spreadsheet::WriteExcel();
+
+my $plotcolors = ['#33ff00', 
+                  '#0033cc', '#990000', '#aaaa66', '#663399', '#ff9933',
+                  '#66ccff', '#ff9999', '#cccc33', '#660000', '#33cc66',
+                  ]; 
 
 sub BuildProblemAnalysisPage {
     my ($r,$c)=@_;
@@ -42,21 +50,60 @@ sub BuildProblemAnalysisPage {
     #
     my @Students = @Apache::lonstatistics::Students;
     #
-    if (exists($ENV{'form.problemchoice'})) {
-        $r->print('<hr />');
+    if (exists($ENV{'form.ClearCache'}) || 
+        exists($ENV{'form.updatecaches'}) ||
+        (exists($ENV{'form.firstanalysis'}) &&
+         $ENV{'form.firstanalysis'} ne 'no')) {
         &Apache::lonstatistics::Gather_Full_Student_Data($r);
+    }
+    if (! exists($ENV{'form.firstanalysis'})) {
+        $r->print('<input type="hidden" name="firstanalysis" value="yes" />');
+    } else {
+        $r->print('<input type="hidden" name="firstanalysis" value="no" />');
+    }
+    $r->rflush();
+    if (exists($ENV{'form.problemchoice'}) && 
+        ! exists($ENV{'form.SelectAnother'})) {
+        $r->print('<input type="submit" name="ProblemAnalysis" value="'.
+                  &mt('Analyze Problem Again').'" />');
+        $r->print('&nbsp;'x5);
+        $r->print('<input type="submit" name="ClearCache" value="'.
+                  &mt('Clear Caches').'" />');
+        $r->print('&nbsp;'x5);
+        $r->print('<input type="submit" name="updatecaches" value="'.
+                  &mt('Update Student Data').'" />');
+        $r->print('&nbsp;'x5);
+        $r->print('<input type="hidden" name="problemchoice" value="'.
+                  $ENV{'form.problemchoice'}.'" />');
+        $r->print('<input type="submit" name="SelectAnother" value="'.
+                  &mt('Choose a different resource').'" />');
+        $r->print('&nbsp;'x5);
+        $r->print('<input type="submit" name="ExcelOutput" value="'.
+                  &mt('Produce Excel Data Sheet').'" />');
+        $r->print('&nbsp;'x5);
+        #
+        $r->print('<hr />');
         #
         my ($symb,$part,$resid) = &get_problem_symb(
                      &Apache::lonnet::unescape($ENV{'form.problemchoice'})
                                            );
-        #
-#        my ($firsttime,$lasttime) = 
-#            &Apache::loncoursedata::get_timestamp_data($symb,$resid);
+        $r->rflush();
         #
         my $resource = &get_resource_from_symb($symb);
         if (defined($resource)) {
+            $r->print('<h3>'.$resource->{'src'}.'</h3>');
             my %Data = &get_problem_data($resource->{'src'});
+            my $PerformanceData = 
+                &Apache::loncoursedata::get_optionresponse_data
+                                           (\@Students,$symb,$resid);
             my $ORdata = $Data{$part.'.'.$resid};
+            if (exists($ENV{'form.ExcelOutput'}) && 
+                defined($PerformanceData)) {
+                my $result = &prepare_excel_sheet($r,$resource,
+                                                  $PerformanceData,$ORdata);
+                $r->print($result);
+                $r->rflush();
+            }
             ##
             ## Render the problem
             my $base;
@@ -64,27 +111,27 @@ sub BuildProblemAnalysisPage {
             $base = "http://".$ENV{'SERVER_NAME'}.$base;
             my $rendered_problem = 
                 &Apache::lonnet::ssi_body($resource->{'src'});
-            $rendered_problem =~ s/<form /<nop /g;
-            $rendered_problem =~ s/<\s*\/form\s>/<\/nop>/g;
+            $rendered_problem =~ s/<\s*form\s*/<nop /g;
+            $rendered_problem =~ s|(<\s*/form\s*>)|<\/nop>|g;
             $r->print('<table bgcolor="ffffff"><tr><td>'.
                       '<base href="'.$base.'" />'.
                       $rendered_problem.
                       '</td></tr></table>');
+            $r->rflush();
             ##
             ## Analyze the problem
-            my $PerformanceData = 
-                &Apache::loncoursedata::get_optionresponse_data
-                                           (\@Students,$symb,$resid);
             if (defined($PerformanceData) && 
                 ref($PerformanceData) eq 'ARRAY') {
-                if ($ENV{'form.AnalyzeBy'} eq 'Tries') {
-                    my $analysis_html = &DoTriesAnalysis($PerformanceData,
+                if ($ENV{'form.AnalyzeOver'} eq 'Tries') {
+                    my $analysis_html = &tries_analysis($r,$PerformanceData,
                                                          $ORdata);
-                $r->print($analysis_html);
-#                } elsif ($ENV{'form.AnalyzeBy'} eq 'Time') {
-#                    my $analysis_html = &DoTimeAnalysis($PerformanceData,
-#                                                         $ORdata);
-#                $r->print($analysis_html);
+                    $r->print($analysis_html);
+                    $r->rflush();
+                } elsif ($ENV{'form.AnalyzeOver'} eq 'Time') {
+                    my $analysis_html = &time_analysis($PerformanceData,
+                                                         $ORdata);
+                    $r->print($analysis_html);
+                    $r->rflush();
                 } else {
                     $r->print('<h2>'.
                               &mt('The analysis you have selected is '.
@@ -101,167 +148,995 @@ sub BuildProblemAnalysisPage {
         }
         $r->print('<hr />');
     } else {
+        $r->print('<input type="submit" name="ProblemAnalysis" value="'.
+                  &mt('Analyze Problem').'" />');
+        $r->print('&nbsp;'x5);
         $r->print('<h3>'.&mt('Please select a problem to analyze').'</h3>');
+        $r->print(&OptionResponseProblemSelector());
     }
-    # Okay, they asked for data, so make sure we get the latest data.
-    $r->print(&OptionResponseProblemSelector());
 }
 
-
-sub DoTriesAnalysis {
-    my ($PerformanceData,$ORdata) = @_;
-    my $mintries = 1;
-    my $maxtries = 10;
-    my %ResponseData = &analyze_option_data_by_tries($PerformanceData,
-                                                 $mintries,$maxtries);
-    my @Foils = sort(keys(%ResponseData));
-    my %Row_Label;
+#########################################################
+#########################################################
+##
+##      Misc interface routines use by analysis code
+##
+#########################################################
+#########################################################
+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) {
-        my $value = $ORdata->{'Foiltext'}->{$foilid};
-#        &Apache::lonnet::logthis('row label '.$foilid.' = '.$value);
-        $Row_Label{$foilid} = $ORdata->{'Foiltext'}->{$foilid};
+        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($Numbers{$a})) {
+            $a1 = $Numbers{$a};
+        }
+        if (exists($Numbers{$b})) {
+            $b1 = $Numbers{$b};
+        }
+        $a1 cmp $b1;
+    };
+    my @Concepts;
+    foreach my $concept (sort $sortfunction (keys(%Concepts))) {
+        push(@Concepts,{ name => $concept,
+                        foils => [@{$Concepts{$concept}}]});
+        push(@Foils,(@{$Concepts{$concept}}));
+    }
+    #
+    # Build up the table of row labels.
+    my $table = '<table border="1" >'."\n";
+    if (@Concepts > 1) {
+        $table .= '<tr>'.
+            '<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>'.
+            "</tr>\n";
+    } else {
+        $table .= '<tr>'.
+            '<th>'.&mt('Foil Number').'</th>'.
+            '<th>'.&mt('Foil Name').'</th>'.
+            '<th>'.&mt('Foil Text').'</th>'.
+            '<th>'.&mt('Correct Value').'</th>'.
+            "</tr>\n";
+    }        
+    my $conceptindex = 1;
+    my $foilindex = 1;
+    foreach my $concept (@Concepts) {
+        my @FoilsInConcept = @{$concept->{'foils'}};
+        my $firstfoil = shift(@FoilsInConcept);
+        if (@Concepts > 1) {
+            $table .= '<tr>'.
+                '<td>'.$conceptindex.'</td>'.
+                '<td>'.$concept->{'name'}.'</td>'.
+                '<td>'.$foilindex++.'</td>'.
+                '<td>'.$Foildata{$firstfoil}->{'name'}.'</td>'.
+                '<td>'.$Foildata{$firstfoil}->{'text'}.'</td>'.
+                '<td>'.$Foildata{$firstfoil}->{'value'}.'</td>'.
+                "</tr>\n";
+        } else {
+            $table .= '<tr>'.
+                '<td>'.$foilindex++.'</td>'.
+                '<td>'.$Foildata{$firstfoil}->{'name'}.'</td>'.
+                '<td>'.$Foildata{$firstfoil}->{'text'}.'</td>'.
+                '<td>'.$Foildata{$firstfoil}->{'value'}.'</td>'.
+                "</tr>\n";
+        }
+        foreach my $foilid (@FoilsInConcept) {
+            if (@Concepts > 1) {
+                $table .= '<tr>'.
+                    '<td></td>'.
+                    '<td></td>'.
+                    '<td>'.$foilindex.'</td>'.
+                    '<td>'.$Foildata{$foilid}->{'name'}.'</td>'.
+                    '<td>'.$Foildata{$foilid}->{'text'}.'</td>'.
+                    '<td>'.$Foildata{$foilid}->{'value'}.'</td>'.
+                    "</tr>\n";
+            } else {
+                $table .= '<tr>'.
+                    '<td>'.$foilindex.'</td>'.
+                    '<td>'.$Foildata{$foilid}->{'name'}.'</td>'.
+                    '<td>'.$Foildata{$foilid}->{'text'}.'</td>'.
+                    '<td>'.$Foildata{$foilid}->{'value'}.'</td>'.
+                    "</tr>\n";
+            }                
+        } continue {
+            $foilindex++;
+        }
+    } continue {
+        $conceptindex++;
     }
+    $table .= "</table>\n";
+    #
+    # Build option index with color stuff
+    return ($table,\@Foils,\@Concepts);
+}
+
+sub build_option_index {
+    my ($ORdata)= @_;
+    my $table = "<table>\n";
+    my $optionindex = 0;
     my @Rows;
-    $Rows[0] = ['<td>&nbsp;</td>'];
-    for (my $i=$mintries;$i<=$maxtries;$i++) {
-        push (@{$Rows[0]},
-              '<th colspan="3">'.&mt('Attempt').' '.$i.'</th>');
+    foreach my $option (&mt('correct option chosen'),@{$ORdata->{'Options'}}) {
+        push (@Rows,
+              '<tr>'.
+              '<td bgcolor="'.$plotcolors->[$optionindex++].'">'.
+              ('&nbsp;'x4).'</td>'.
+              '<td>'.$option.'</td>'.
+              "</tr>\n");
+    }
+    shift(@Rows); # Throw away 'correct option chosen' color
+    $table .= join('',reverse(@Rows));
+    $table .= "</table>\n";
+}
+
+#########################################################
+#########################################################
+##
+##         Tries Analysis
+##
+#########################################################
+#########################################################
+sub tries_analysis {
+    my ($r,$PerformanceData,$ORdata) = @_;
+    my $mintries = 1;
+    my $maxtries = $ENV{'form.NumPlots'};
+    my ($table,$Foils,$Concepts) = &build_foil_index($ORdata);
+    if ((@$Concepts < 2) && ($ENV{'form.AnalyzeAs'} ne 'Foils')) {
+        $table = '<h3>'.
+            &mt('Not enough data for concept analysis.  '.
+                'Performing Foil Analysis').
+            '</h3>'.$table;
+        $ENV{'form.AnalyzeAs'} = 'Foils';
+    }
+    my %ResponseData = &analyze_option_data_by_tries($r,$PerformanceData,
+                                                     $mintries,$maxtries);
+    my $analysis = '';
+    if ($ENV{'form.AnalyzeAs'} eq 'Foils') {
+        $analysis = &Tries_Foil_Analysis($mintries,$maxtries,$Foils,
+                                         \%ResponseData,$ORdata);
+    } else {
+        $analysis = &Tries_Concept_Analysis($mintries,$maxtries,
+                                            $Concepts,\%ResponseData,$ORdata);
+    }
+    $table .= $analysis;
+    return $table;
+}
+
+sub Tries_Foil_Analysis {
+    my ($mintries,$maxtries,$Foils,$respdat,$ORdata) = @_;
+    my %ResponseData = %$respdat;
+    #
+    # Compute the data neccessary to make the plots
+    my @PlotData; 
+    foreach my $foilid (@$Foils) {
+        for (my $i=$mintries;$i<=$maxtries;$i++) {
+            if ($ResponseData{$foilid}->[$i]->{'_total'} == 0) {
+                push(@{$PlotData[$i]->{'_correct'}},0);
+            } else {
+                push(@{$PlotData[$i]->{'_correct'}},
+                     100*$ResponseData{$foilid}->[$i]->{'_correct'}/
+                     $ResponseData{$foilid}->[$i]->{'_total'});
+            }
+            foreach my $option (@{$ORdata->{'Options'}}) {
+                push(@{$PlotData[$i]->{'_total'}},
+                     $ResponseData{$foilid}->[$i]->{'_total'});
+                if ($ResponseData{$foilid}->[$i]->{'_total'} == 0) {
+                    push (@{$PlotData[$i]->{$option}},0);
+                } else {
+                    if ($ResponseData{$foilid}->[$i]->{'_total'} ==
+                        $ResponseData{$foilid}->[$i]->{'_correct'}) {
+                        push(@{$PlotData[$i]->{$option}},0);
+                    } else {
+                        push (@{$PlotData[$i]->{$option}},
+                              100 * $ResponseData{$foilid}->[$i]->{$option} / 
+                              ($ResponseData{$foilid}->[$i]->{'_total'} - 
+                               $ResponseData{$foilid}->[$i]->{'_correct'}));
+                    }
+                }
+            }
+        }
     }
-    $Rows[1] = ['<th>'.&mt('Foil').'</th>'];
+    # 
+    # Build a table for the plots
+    my $analysis_html = "<table>\n";
+    my $foilkey = &build_option_index($ORdata);
     for (my $i=$mintries;$i<=$maxtries;$i++) {
-        push (@{$Rows[1]},('<th>'.&mt('Correct').'</th>',
-                           '<th>'.&mt('Incorrect').'</th>',
-                           '<th>'.&mt('Percent Correct').'</th>',
-                           ));
+        my $count = $ResponseData{'_total'}->[$i];
+        if ($count == 0) {
+            $count = 'no submissions';
+        } elsif ($count == 1) {
+            $count = '1 submission';
+        } else {
+            $count = $count.' submissions';
+        }
+        my $title = 'Attempt '.$i.', '.$count;
+        my @Datasets;
+        foreach my $option ('_correct',@{$ORdata->{'Options'}}) {
+            next if (! exists($PlotData[$i]->{$option}));
+            push(@Datasets,$PlotData[$i]->{$option});
+        }
+        my $correctgraph = &Apache::loncommon::DrawGraph
+            ($title,'Foil Number','Percent Correct',
+             100,$plotcolors,$Datasets[0]);
+        $analysis_html.= '<tr><td>'.$correctgraph.'</td>';
+        ##
+        ##
+        for (my $i=0; $i< scalar(@{$Datasets[0]});$i++) {
+            $Datasets[0]->[$i]=0;
+        }
+        $count = $ResponseData{'_total'}->[$i]-$ResponseData{'_correct'}->[$i];
+        if ($count == 0) {
+            $count = 'no submissions';
+        } elsif ($count == 1) {
+            $count = '1 submission';
+        } else {
+            $count = $count.' submissions';
+        }
+        $title = 'Attempt '.$i.', '.$count;
+        my $incorrectgraph = &Apache::loncommon::DrawGraph
+            ($title,'Foil Number','% Option Chosen Incorrectly',
+             100,$plotcolors,@Datasets);
+        $analysis_html.= '<td>'.$incorrectgraph.'</td>';
+        $analysis_html.= '<td>'.$foilkey."<td></tr>\n";
     }
+    $analysis_html .= "</table>\n";
+    return $analysis_html;
+}
+
+sub Tries_Concept_Analysis {
+    my ($mintries,$maxtries,$Concepts,$respdat,$ORdata) = @_;
+    my %ResponseData = %$respdat;
+    my $analysis_html = "<table>\n";
+    #
+    # Compute the data neccessary to make the plots
     my @PlotData;
-    my @CumulativePlotData;
-    my $index = 1;
-    foreach my $foilid (@Foils) {
-        my @Data = ('<td>'.$index.' '.$Row_Label{$foilid}.'</td>');
+    # Concept analysis
+    #
+    # Note: we do not bother with characterizing the students incorrect
+    # answers at the concept level because an incorrect answer for one foil
+    # may be a correct answer for another foil.
+    my %ConceptData;
+    foreach my $concept (@{$Concepts}) {
         for (my $i=$mintries;$i<=$maxtries;$i++) {
-            push(@Data,
-                 ('<td>'.$ResponseData{$foilid}->[$i]->{'correct'}.'</td>',
-                  '<td>'.$ResponseData{$foilid}->[$i]->{'incorrect'}.
-                  '</td>',
-                  '<td>'.
-                  sprintf("%4.2f",
-                          $ResponseData{$foilid}->[$i]->{'percent_corr'}).
-                  '</td>'));
             #
             # Gather the per-attempt data
-            push (@{$PlotData[$i]->{'good'}},
-                  $ResponseData{$foilid}->[$i]->{'percent_corr'});
-            push (@{$PlotData[$i]->{'bad'}},
-                  100-$ResponseData{$foilid}->[$i]->{'percent_corr'});
-        }
-        for (my $i=0;$i<=$maxtries;$i++) {
-            push (@{$CumulativePlotData[$i]->{'good'}},
-                  $CumulativePlotData[-1]->{'good'}+
-                  $ResponseData{$foilid}->[$i]->{'correct'});
-            push (@{$CumulativePlotData[$i]->{'bad'}},
-                  $CumulativePlotData[-1]->{'bad'}+
-                  $ResponseData{$foilid}->[$i]->{'incorrect'});
+            my $cdata = $ConceptData{$concept}->[$i];
+            foreach my $foilid (@{$concept->{'foils'}}) {
+                $cdata->{'_correct'} += 
+                    $ResponseData{$foilid}->[$i]->{'_correct'};
+                $cdata->{'_total'}   += 
+                    $ResponseData{$foilid}->[$i]->{'_total'};
+            }
+            push (@{$PlotData[$i]->{'_total'}},$cdata->{'_total'});
+            if ($cdata->{'_total'} == 0) {
+                push (@{$PlotData[$i]->{'_correct'}},0);
+            } else {
+                push (@{$PlotData[$i]->{'_correct'}},
+                      100*$cdata->{'_correct'}/$cdata->{'_total'});
+                }
         }
-        push(@Rows,\@Data);
-    } continue {
-        $index++;
     }
-    my @Data = ('<td></td>');
+    # Build a table for the plots
     for (my $i=$mintries;$i<=$maxtries;$i++) {
-        my $minstu = $ResponseData{$Foils[0]}->[$i]->{'total'};
-        my $maxstu = $ResponseData{$Foils[0]}->[$i]->{'total'};
-        foreach my $foilid (@Foils) {
-            if ($minstu > $ResponseData{$foilid}->[$i]->{'total'}) {
-                $minstu = $ResponseData{$foilid}->[$i]->{'total'};
-            }
-            if ($maxstu < $ResponseData{$foilid}->[$i]->{'total'}) {
-                $maxstu = $ResponseData{$foilid}->[$i]->{'total'};
-            }
-        }
-        $maxstu = 0 if (! $maxstu);
-        $minstu = 0 if (! $minstu);
-        my $graphlink;
-        if ($maxstu == $minstu) {
-            $graphlink = &Apache::loncommon::DrawGraph
-                ('Attempt '.$i.', '.$maxstu.' students',
-                 'Foil Number',
-                 'Percent Correct',
-                 100,
-                 $PlotData[$i]->{'good'},
-                 $PlotData[$i]->{'bad'});
+        my $minstu = $PlotData[$i]->{'_total'}->[0];
+        my $maxstu = $PlotData[$i]->{'_total'}->[0];
+        foreach my $count (@{$PlotData[$i]->{'_total'}}) {
+            if ($minstu > $count) {
+                $minstu = $count;
+            }
+            if ($maxstu < $count) {
+                $maxstu = $count;
+            }
+        }
+        $maxstu = 0 if (! defined($maxstu));
+        $minstu = 0 if (! defined($minstu));
+        my $title;
+        my $count = $ResponseData{'_total'}->[$i];
+        if ($count == 0) {
+            $count = 'no submissions';
+        } elsif ($count == 1) {
+            $count = '1 submission';
         } else {
-            $graphlink = &Apache::loncommon::DrawGraph
-                ('Attempt '.$i.', '.$minstu.'-'.$maxstu.
-                 ' students',
-                 'Foil Number',
-                 'Percent Correct',
-                 100,
-                 $PlotData[$i]->{'good'},
-                 $PlotData[$i]->{'bad'});
+            $count = $count.' submissions';
         }
-        push(@Data,'<td colspan="3">'.$graphlink.'</td>');
+        $title = 'Attempt '.$i.', '.$count;
+        my $graphlink = &Apache::loncommon::DrawGraph
+            ($title,'Concept Number','Percent Correct',
+             100,$plotcolors,$PlotData[$i]->{'_correct'});
+        $analysis_html.= '<tr><td>'.$graphlink."</td></tr>\n";
     }
-    push (@Rows,\@Data);
-    my $table = '<table border="1" >'."\n";
-    for (my $i=0; $i <=$#Rows;$i++) {
-        $table .= '<tr>'.join('',@{$Rows[$i]})."</tr>\n";
-    }
-    $table .= '</table>';
-    return ($table);
+    $analysis_html .= "</table>\n";
+    return $analysis_html;
 }
 
 sub analyze_option_data_by_tries {
-    my ($PerformanceData,$mintries,$maxtries) = @_;
+    my ($r,$PerformanceData,$mintries,$maxtries) = @_;
     my %Trydata;
     $mintries = 1         if (! defined($mintries) || $mintries < 1);
     $maxtries = $mintries if (! defined($maxtries) || $maxtries < $mintries);
     foreach my $row (@$PerformanceData) {
         next if (! defined($row));
-        my ($grading,$submission,$time,$tries) = @$row;
-        my @Foilgrades = split('&',$grading);
-        my @Foilsubs   = split('&',$submission);
-        for (my $numtries = 1; $numtries <= $maxtries; $numtries++) {
-            if ($tries == $numtries) {
-                foreach my $foilgrade (@Foilgrades) {
-                    my ($foilid,$correct) = split('=',$foilgrade);
-                    if ($correct) {
-                        $Trydata{$foilid}->[$numtries]->{'correct'}++;
-                    } else {
-                        $Trydata{$foilid}->[$numtries]->{'incorrect'}++;
-                    }                        
-                }
+        my $tries = &get_tries_from_row($row);
+        my %Row   = &Process_Row($row);
+        next if (! %Row);
+        while (my ($foilid,$href) = each(%Row)) {
+            if (! ref($href)) { 
+                $Trydata{$foilid}->[$tries] += $href;
+                next;
+            }
+            while (my ($option,$value) = each(%$href)) {
+                $Trydata{$foilid}->[$tries]->{$option}+=$value;
             }
         }
     }
-    foreach my $foilid (keys(%Trydata)) {
-        foreach my $tryhash (@{$Trydata{$foilid}}) {
-            next if ((! exists($tryhash->{'correct'}) && 
-                      ! exists($tryhash->{'incorrect'})) ||
-                     ($tryhash->{'correct'} < 1 &&
-                      $tryhash->{'incorrect'} < 1));
-            $tryhash->{'total'} = $tryhash->{'correct'} + 
-                                        $tryhash->{'incorrect'};
-            $tryhash->{'percent_corr'} = 100 *
-                ($tryhash->{'correct'} /
-                         ($tryhash->{'correct'} + $tryhash->{'incorrect'})
-                 );
+    return %Trydata;
+}
+
+#########################################################
+#########################################################
+##
+##                 Time Analysis
+##
+#########################################################
+#########################################################
+sub time_analysis {
+    my ($PerformanceData,$ORdata) = @_;
+    my ($table,$Foils,$Concepts) = &build_foil_index($ORdata);
+    if ((@$Concepts < 2) && ($ENV{'form.AnalyzeAs'} ne 'Foils')) {
+        $table = '<h3>'.
+            &mt('Not enough data for concept analysis.  '.
+                'Performing Foil Analysis').
+            '</h3>'.$table;
+        $ENV{'form.AnalyzeAs'} = 'Foils';
+    }
+    my $num_plots = $ENV{'form.NumPlots'};
+    my $num_data = scalar(@$PerformanceData)-1;
+    my $percent = sprintf('%2f',100/$num_plots);
+    #
+    $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 $last_sub_time = &get_time_from_row($PerformanceData->[-1]);
+            my ($sday,$smon,$syear);
+            (undef,undef,undef,$sday,$smon,$syear) = 
+                localtime($last_sub_time - $sec_in_day*$i);
+            $starttime = &Time::Local::timelocal(0,0,0,$sday,$smon,$syear);
+            $endtime = $starttime + $sec_in_day;
+            if ($i == ($num_plots -1 )) {
+                $starttime = &get_time_from_row($PerformanceData->[0]);
+            }
+        }
+        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(@$PerformanceData)) {
+            last if (&get_time_from_row($PerformanceData->[$j]) > $starttime);
+        }
+        $begin_index = $j;
+        while (++$j < scalar(@$PerformanceData)) {
+            last if (&get_time_from_row($PerformanceData->[$j]) > $endtime);
+        }
+        $end_index = $j;
+        ##
+        my $interval = {
+            begin_index => $begin_index,
+            end_index   => $end_index,
+            startdateform => $startdateform,
+            enddateform   => $enddateform,
+        };
+        if ($ENV{'form.AnalyzeAs'} eq 'Foils') {
+            $table .= &Foil_Time_Analysis($PerformanceData,$ORdata,$Foils,
+                                          $interval);
+        } else {
+            $table .= &Concept_Time_Analysis($PerformanceData,$ORdata,
+                                             $Concepts,$interval);
         }
     }
-    return %Trydata;
+    #
+    return $table;
 }
 
-sub get_problem_symb {
-    my $problemstring = shift();
-    my ($symb,$partid,$resid) = ($problemstring=~ /^(.*):([^:]*):([^:]*)$/);
-    return ($symb,$partid,$resid);
+sub Foil_Time_Analysis {
+    my ($PerformanceData,$ORdata,$Foils,$interval) = @_;
+    my $analysis_html;
+    my $foilkey = &build_option_index($ORdata);
+    my ($begin_index,$end_index) = ($interval->{'begin_index'},
+                                    $interval->{'end_index'});
+    my %TimeData;
+    #
+    # Compute the number getting the foils correct or incorrects
+    for (my $j=$begin_index;$j<=$end_index;$j++) {
+        my $row = $PerformanceData->[$j];
+        next if (! defined($row));
+        my %Row = &Process_Row($row);
+        while (my ($foilid,$href) = each(%Row)) {
+            if (! ref($href)) {
+                $TimeData{$foilid} += $href;
+                next;
+            }
+            while (my ($option,$value) = each(%$href)) {
+                $TimeData{$foilid}->{$option}+=$value;
+            }
+        }
+    }
+    my @Plotdata;
+    foreach my $foil (@$Foils) {
+        my $total = $TimeData{$foil}->{'_total'};
+        if ($total == 0) {
+            push(@{$Plotdata[0]},0);
+        } else {
+            push(@{$Plotdata[0]},
+                 100 * $TimeData{$foil}->{'_correct'} / $total);
+        }
+        my $total_incorrect = $total - $TimeData{$foil}->{'_correct'};
+        my $optionidx = 1;
+        foreach my $option (@{$ORdata->{'Options'}}) {
+            if ($total_incorrect == 0) {
+                push(@{$Plotdata[$optionidx]},0);
+            } else {
+                push(@{$Plotdata[$optionidx]},
+                     100 * $TimeData{$foil}->{$option} / $total_incorrect);
+            }
+        } continue {
+            $optionidx++;
+        }
+    }
+    #
+    # Create the plot
+    my $count = $end_index-$begin_index;
+    my $title;
+    if ($count == 0) {
+        $title = 'no submissions';
+    } elsif ($count == 1) {
+        $title = 'one submission';
+    } else {
+        $title = $count.' submissions';
+    }
+    my $correctplot = &Apache::loncommon::DrawGraph($title,
+                                                    'Foil Number',
+                                                    'Percent Correct',
+                                                    100,
+                                                    $plotcolors,
+                                                    $Plotdata[0]);
+    for (my $j=0; $j< scalar(@{$Plotdata[0]});$j++) {
+        $Plotdata[0]->[$j]=0;
+    }
+    $count = $end_index-$begin_index-$TimeData{'_correct'};
+    if ($count == 0) {
+        $title = 'no submissions';
+    } elsif ($count == 1) {
+        $title = 'one submission';
+    } else {
+        $title = $count.' submissions';
+    }
+    my $incorrectplot = &Apache::loncommon::DrawGraph($title,
+                                                 'Foil Number',
+                                                 'Incorrect Option Choice',
+                                                 100,
+                                                 $plotcolors,
+                                                 @Plotdata);        
+    $analysis_html.='<tr>'.
+        '<td>'.$correctplot.'</td>'.
+        '<td>'.$incorrectplot.'</td>'.
+        '<td align="left" valign="top">'.$foilkey.'</td>'."</tr>\n";
+    $analysis_html.= '<tr>'.'<td colspan="3">'.
+        '<b>Start Time</b>:'.
+        ' &nbsp;'.$interval->{'startdateform'}.'<br />'.
+        '<b>End Time</b>&nbsp;&nbsp;: '.
+        '&nbsp;'.$interval->{'enddateform'}.'<br />'.
+#        '<b>Plot Title</b>&nbsp;&nbsp;:'.
+#        ("&nbsp;"x3).$interval->{'titleform'}.
+        '</td>'.
+        "</tr>\n";
+    return $analysis_html;
+}
+
+sub Concept_Time_Analysis {
+    my ($PerformanceData,$ORdata,$Concepts,$interval) = @_;
+    my $analysis_html;
+    ##
+    ## Determine starttime, endtime, startindex, endindex
+    my ($begin_index,$end_index) = ($interval->{'begin_index'},
+                                    $interval->{'end_index'});
+    my %TimeData;
+    #
+    # Compute the number getting the foils correct or incorrects
+    for (my $j=$begin_index;$j<=$end_index;$j++) {
+        my $row = $PerformanceData->[$j];
+        next if (! defined($row));
+        my %Row = &Process_Row($row);
+        while (my ($foilid,$href) = each(%Row)) {
+            if (! ref($href)) {
+                $TimeData{$foilid} += $href;
+                next;
+            }
+            while (my ($option,$value) = each(%$href)) {
+                $TimeData{$foilid}->{$option}+=$value;
+            }
+        }
+    }
+    #
+    # Put the data in plottable form
+    my @Plotdata;
+    foreach my $concept (@$Concepts) {
+        my ($total,$correct);
+        foreach my $foil (@{$concept->{'foils'}}) {
+            $total += $TimeData{$foil}->{'_total'};
+            $correct += $TimeData{$foil}->{'_correct'};
+        }
+        if ($total == 0) {
+            push(@Plotdata,0);
+        } else {
+            push(@Plotdata,100 * $correct / $total);
+        }
+    }
+    #
+    # Create the plot
+    my $title = ($end_index - $begin_index).' submissions';
+    my $correctplot = &Apache::loncommon::DrawGraph($title,
+                                                    'Concept Number',
+                                                    'Percent Correct',
+                                                    100,
+                                                    $plotcolors,
+                                                    \@Plotdata);
+    $analysis_html.='<tr>'.
+        '<td>'.$correctplot.'</td>'.
+        '<td align="left" valign="top">'.
+        '<b>Start Time</b>: &nbsp;'.$interval->{'startdateform'}.'<br />'.
+        '<b>End Time</b>&nbsp;&nbsp;: '.
+           '&nbsp;'.$interval->{'enddateform'}.'<br />'.
+#        '<b>Plot Title</b>&nbsp;&nbsp;:'.("&nbsp;"x3).
+#            $interval->{'titleform'}.
+        '</td>'.
+        "</tr>\n";
+    return $analysis_html;
+}
+
+#########################################################
+#########################################################
+##
+##             Excel output 
+##
+#########################################################
+#########################################################
+
+sub prepare_excel_sheet {
+    my ($r,$resource,$PerformanceData,$ORdata) = @_;
+    my $response = '<h2>'.&mt('Excel Spreadsheet Creation').'</h2>';
+    my (undef,$Foils,$Concepts) = &build_foil_index($ORdata);
+    #
+    # Create excel worksheet
+    my $filename = '/prtspool/'.
+        $ENV{'user.name'}.'_'.$ENV{'user.domain'}.'_'.
+        time.'_'.rand(1000000000).'.xls';
+    my $workbook  = Spreadsheet::WriteExcel->new('/home/httpd'.$filename);
+    if (! defined($workbook)) {
+        $r->log_error("Error creating excel spreadsheet $filename: $!");
+        $r->print('<p>'.&mt("Unable to create new Excel file.  ".
+                            "This error has been logged.  ".
+                            "Please alert your LON-CAPA administrator").
+                  '</p>');
+        return undef;
+    }
+    #
+    $workbook->set_tempdir('/home/httpd/perl/tmp');
+    #
+    # Define some potentially useful formats
+    my $format;
+    $format->{'header'} = $workbook->add_format(bold      => 1, 
+                                                bottom    => 1,
+#                                                text_wrap => 1,
+                                                align     => 'center');
+    $format->{'bold'} = $workbook->add_format(bold=>1);
+    $format->{'h1'}   = $workbook->add_format(bold=>1, size=>18);
+    $format->{'h2'}   = $workbook->add_format(bold=>1, size=>16);
+    $format->{'h3'}   = $workbook->add_format(bold=>1, size=>14);
+    $format->{'date'} = $workbook->add_format(num_format=>
+                                              'mmm d yyyy hh:mm AM/PM');
+    #
+    # Create and populate main worksheets
+    my $problem_data_sheet  = $workbook->addworksheet('Problem Data');
+    my $student_data_sheet  = $workbook->addworksheet('Student Data');
+    my $response_data_sheet = $workbook->addworksheet('Response Data');
+    foreach my $sheet ($problem_data_sheet,$student_data_sheet,
+                       $response_data_sheet) {
+        $sheet->write(0,0,$resource->{'title'},$format->{'h2'});
+        $sheet->write(1,0,$resource->{'src'},$format->{'h3'});
+    }
+    #
+    my $result;
+    $result = &build_problem_data_worksheet($problem_data_sheet,$format,
+                                            $Concepts,$ORdata);
+    if ($result ne 'okay') {
+        # Do something useful
+    }
+    $result = &build_student_data_worksheet($student_data_sheet,$format);
+    if ($result ne 'okay') {
+        # Do something useful
+    }
+    $result = &build_response_data_worksheet($response_data_sheet,$format,
+                                             $PerformanceData,$Foils,
+                                             $ORdata);
+    if ($result ne 'okay') {
+        # Do something useful
+    }
+   $response_data_sheet->activate();
+    #
+    # Close the excel file
+    $workbook->close();
+    #
+    # Write a link to allow them to download it
+    $result .= '<br />'.
+              '<a href="'.$filename.'">Your Excel spreadsheet.</a>'."\n";
+    return $result;
 }
 
+sub build_problem_data_worksheet {
+    my ($worksheet,$format,$Concepts,$ORdata) = @_;
+    my $rows_output = 3;
+    my $cols_output = 0;
+    $worksheet->write($rows_output++,0,'Problem Structure',$format->{'h3'});
+    ##
+    ##
+    my @Headers;
+    if (@$Concepts > 1) {
+        @Headers = ("Concept\nNumber",'Concept',"Foil\nNumber",
+                    'Foil Name','Foil Text','Correct value');
+    } else {
+        @Headers = ('Foil Number','FoilName','Foil Text','Correct value');
+    }
+    $worksheet->write_row($rows_output++,0,\@Headers,$format->{'header'});
+    my %Foildata = %{$ORdata->{'Foils'}};
+    my $conceptindex = 1;
+    my $foilindex = 1;
+    foreach my $concept (@$Concepts) {
+        my @FoilsInConcept = @{$concept->{'foils'}};
+        my $firstfoil = shift(@FoilsInConcept);
+        if (@$Concepts > 1) {
+            $worksheet->write_row($rows_output++,0,
+                                  [$conceptindex,
+                                   $concept->{'name'},
+                                   $foilindex++,
+                                   $Foildata{$firstfoil}->{'name'},
+                                   $Foildata{$firstfoil}->{'text'},
+                                   $Foildata{$firstfoil}->{'value'},]);
+        } else {
+            $worksheet->write_row($rows_output++,0,
+                                  [ $foilindex++,
+                                    $Foildata{$firstfoil}->{'name'},
+                                    $Foildata{$firstfoil}->{'text'},
+                                    $Foildata{$firstfoil}->{'value'},]);
+        }
+        foreach my $foilid (@FoilsInConcept) {
+            if (@$Concepts > 1) {
+                $worksheet->write_row($rows_output++,0,
+                                      ['',
+                                       '',
+                                       $foilindex,
+                                       $Foildata{$foilid}->{'name'},
+                                       $Foildata{$foilid}->{'text'},
+                                       $Foildata{$foilid}->{'value'},]);
+            } else {
+                $worksheet->write_row($rows_output++,0,                
+                                      [$foilindex,
+                                       $Foildata{$foilid}->{'name'},
+                                       $Foildata{$foilid}->{'text'},
+                                       $Foildata{$foilid}->{'value'},]);
+            }                
+        } continue {
+            $foilindex++;
+        }
+    } continue {
+        $conceptindex++;
+    }
+    $rows_output++;
+    $rows_output++;
+    ##
+    ## Option data output
+    $worksheet->write($rows_output++,0,'Options',$format->{'header'});
+    foreach my $string (@{$ORdata->{'Options'}}) {
+        $worksheet->write($rows_output++,0,$string);
+    }
+    return 'okay';
+}
+
+sub build_student_data_worksheet {
+    my ($worksheet,$format) = @_;
+    my $rows_output = 3;
+    my $cols_output = 0;
+    $worksheet->write($rows_output++,0,'Student Data',$format->{'h3'});
+    my @Headers = ('full name','username','domain','section',
+                   "student\nnumber",'identifier');
+    $worksheet->write_row($rows_output++,0,\@Headers,$format->{'header'});
+    my @Students = @Apache::lonstatistics::Students;
+    my $studentrows = &Apache::loncoursedata::get_student_data(\@Students);
+    my %ids;
+    foreach my $row (@$studentrows) {
+        my ($mysqlid,$student) = @$row;
+        $ids{$student}=$mysqlid;
+    }
+    foreach my $student (@Students) {
+        my $name_domain = $student->{'username'}.':'.$student->{'domain'};
+        $worksheet->write_row($rows_output++,0,
+                          [$student->{'fullname'},
+                           $student->{'username'},$student->{'domain'},
+                           $student->{'section'},$student->{'id'},
+                           $ids{$name_domain}]);
+    }
+    return;
+}
+
+sub build_response_data_worksheet {
+    my ($worksheet,$format,$PerformanceData,$Foils,$ORdata)=@_;
+    my $rows_output = 3;
+    my $cols_output = 0;
+    $worksheet->write($rows_output++,0,'Response Data',$format->{'h3'});
+    $worksheet->set_column(1,1,20);
+    $worksheet->set_column(2,2,13);
+    my @Headers = ('identifier','time','award detail','attempt');
+    foreach my $foil (@$Foils) {
+        push (@Headers,$foil.' submission');
+        push (@Headers,$foil.' grading');
+    }
+    $worksheet->write_row($rows_output++,0,\@Headers,$format->{'header'});
+    #
+    foreach my $row (@$PerformanceData) {
+        next if (! defined($row));
+        my ($student,$award,$grading,$submission,$time,$tries) = @$row;
+        my @Foilgrades = split('&',$grading);
+        my @Foilsubs   = split('&',$submission);
+        my %ResponseData;
+        for (my $j=0;$j<=$#Foilgrades;$j++) {
+            my ($foilid,$correct)  = split('=',$Foilgrades[$j]);
+            my (undef,$submission) = split('=',$Foilsubs[$j]);
+            $submission = &Apache::lonnet::unescape($submission);
+            $ResponseData{$foilid.' submission'}=$submission;
+            $ResponseData{$foilid.' award'}=$correct;
+        }
+        $worksheet->write($rows_output,$cols_output++,$student);
+        $worksheet->write($rows_output,$cols_output++,
+                          &calc_serial($time),$format->{'date'});
+        $worksheet->write($rows_output,$cols_output++,$award);
+        $worksheet->write($rows_output,$cols_output++,$tries);
+        foreach my $foilid (@$Foils) {
+            $worksheet->write($rows_output,$cols_output++,
+                              $ResponseData{$foilid.' submission'});
+            $worksheet->write($rows_output,$cols_output++,
+                              $ResponseData{$foilid.' award'});
+        }
+        $rows_output++;
+        $cols_output = 0;
+    }
+    return;
+}
+
+
+##
+## The following is copied from datecalc1.pl, part of the 
+## Spreadsheet::WriteExcel CPAN module.
+##
+##
+######################################################################
+#
+# Demonstration of writing date/time cells to Excel spreadsheets,
+# using UNIX/Perl time as source of date/time.
+#
+# Copyright 2000, Andrew Benham, adsb@bigfoot.com
+#
+######################################################################
+#
+# UNIX/Perl time is the time since the Epoch (00:00:00 GMT, 1 Jan 1970)
+# measured in seconds.
+#
+# An Excel file can use exactly one of two different date/time systems.
+# In these systems, a floating point number represents the number of days
+# (and fractional parts of the day) since a start point. The floating point
+# number is referred to as a 'serial'.
+# The two systems ('1900' and '1904') use different starting points:
+#  '1900'; '1.00' is 1 Jan 1900 BUT 1900 is erroneously regarded as
+#          a leap year - see:
+#            http://support.microsoft.com/support/kb/articles/Q181/3/70.asp
+#          for the excuse^H^H^H^H^H^Hreason.
+#  '1904'; '1.00' is 2 Jan 1904.
+#
+# The '1904' system is the default for Apple Macs. Windows versions of
+# Excel have the option to use the '1904' system.
+#
+# Note that Visual Basic's "DateSerial" function does NOT erroneously
+# regard 1900 as a leap year, and thus its serials do not agree with
+# the 1900 serials of Excel for dates before 1 Mar 1900.
+#
+# Note that StarOffice (at least at version 5.2) does NOT erroneously
+# regard 1900 as a leap year, and thus its serials do not agree with
+# the 1900 serials of Excel for dates before 1 Mar 1900.
+#
+######################################################################
+#
+# Calculation description
+# =======================
+#
+# 1900 system
+# -----------
+# Unix time is '0' at 00:00:00 GMT 1 Jan 1970, i.e. 70 years after 1 Jan 1900.
+# Of those 70 years, 17 (1904,08,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68)
+# were leap years with an extra day.
+# Thus there were 17 + 70*365 days = 25567 days between 1 Jan 1900 and
+# 1 Jan 1970.
+# In the 1900 system, '1' is 1 Jan 1900, but as 1900 was not a leap year
+# 1 Jan 1900 should really be '2', so 1 Jan 1970 is '25569'.
+#
+# 1904 system
+# -----------
+# Unix time is '0' at 00:00:00 GMT 1 Jan 1970, i.e. 66 years after 1 Jan 1904.
+# Of those 66 years, 17 (1904,08,12,16,20,24,28,32,36,40,44,48,52,56,60,64,68)
+# were leap years with an extra day.
+# Thus there were 17 + 66*365 days = 24107 days between 1 Jan 1904 and
+# 1 Jan 1970.
+# In the 1904 system, 2 Jan 1904 being '1', 1 Jan 1970 is '24107'.
+#
+######################################################################
+#
+# Copyright (c) 2000, Andrew Benham.
+# This program is free software. It may be used, redistributed and/or
+# modified under the same terms as Perl itself.
+#
+# Andrew Benham, adsb@bigfoot.com
+# London, United Kingdom
+# 11 Nov 2000
+#
+######################################################################
+
+# Use 1900 date system on all platforms other than Apple Mac (for which
+# use 1904 date system).
+my $DATE_SYSTEM = ($^O eq 'MacOS') ? 1 : 0;
+
+#-----------------------------------------------------------
+# calc_serial()
+#
+# Called with (up to) 2 parameters.
+#   1.  Unix timestamp.  If omitted, uses current time.
+#   2.  GMT flag. Set to '1' to return serial in GMT.
+#       If omitted, returns serial in appropriate timezone.
+#
+# Returns date/time serial according to $DATE_SYSTEM selected
+#-----------------------------------------------------------
+sub calc_serial {
+        my $time = (defined $_[0]) ? $_[0] : time();
+        my $gmtflag = (defined $_[1]) ? $_[1] : 0;
+
+        # Divide timestamp by number of seconds in a day.
+        # This gives a date serial with '0' on 1 Jan 1970.
+        my $serial = $time / 86400;
+
+        # Adjust the date serial by the offset appropriate to the
+        # currently selected system (1900/1904).
+        if ($DATE_SYSTEM == 0) {        # use 1900 system
+                $serial += 25569;
+        } else {                        # use 1904 system
+                $serial += 24107;
+        }
+
+        unless ($gmtflag) {
+                # Now have a 'raw' serial with the right offset. But this
+                # gives a serial in GMT, which is false unless the timezone
+                # is GMT. We need to adjust the serial by the appropriate
+                # timezone offset.
+                # Calculate the appropriate timezone offset by seeing what
+                # the differences between localtime and gmtime for the given
+                # time are.
+
+                my @gmtime = gmtime($time);
+                my @ltime  = localtime($time);
+
+                # For the first 7 elements of the two arrays, adjust the
+                # date serial where the elements differ.
+                for (0 .. 6) {
+                        my $diff = $ltime[$_] - $gmtime[$_];
+                        if ($diff) {
+                                $serial += _adjustment($diff,$_);
+                        }
+                }
+        }
+
+        # Perpetuate the error that 1900 was a leap year by decrementing
+        # the serial if we're using the 1900 system and the date is prior to
+        # 1 Mar 1900. This has the effect of making serial value '60'
+        # 29 Feb 1900.
+
+        # This fix only has any effect if UNIX/Perl time on the platform
+        # can represent 1900. Many can't.
+
+        unless ($DATE_SYSTEM) {
+                $serial-- if ($serial < 61);    # '61' is 1 Mar 1900
+        }
+        return $serial;
+}
+
+sub _adjustment {
+        # Based on the difference in the localtime/gmtime array elements
+        # number, return the adjustment required to the serial.
+
+        # We only look at some elements of the localtime/gmtime arrays:
+        #    seconds    unlikely to be different as all known timezones
+        #               have an offset of integral multiples of 15 minutes,
+        #               but it's easy to do.
+        #    minutes    will be different for timezone offsets which are
+        #               not an exact number of hours.
+        #    hours      very likely to be different.
+        #    weekday    will differ when localtime/gmtime difference
+        #               straddles midnight.
+        #
+        # Assume that difference between localtime and gmtime is less than
+        # 5 days, then don't have to do maths for day of month, month number,
+        # year number, etc...
+
+        my ($delta,$element) = @_;
+        my $adjust = 0;
+
+        if ($element == 0) {            # Seconds
+                $adjust = $delta/86400;         # 60 * 60 * 24
+        } elsif ($element == 1) {       # Minutes
+                $adjust = $delta/1440;          # 60 * 24
+        } elsif ($element == 2) {       # Hours
+                $adjust = $delta/24;            # 24
+        } elsif ($element == 6) {       # Day of week number
+                # Catch difference straddling Sat/Sun in either direction
+                $delta += 7 if ($delta < -4);
+                $delta -= 7 if ($delta > 4);
+
+                $adjust = $delta;
+        }
+        return $adjust;
+}
+
+#########################################################
+#########################################################
+##
+##             Interface 
+##
+#########################################################
+#########################################################
 sub CreateInterface {
     ##
     ## Environment variable initialization
-    if (! exists$ENV{'form.AnalyzeBy'}) {
-        $ENV{'form.AnalyzeBy'} = 'Tries';
+    if (! exists$ENV{'form.AnalyzeOver'}) {
+        $ENV{'form.AnalyzeOver'} = 'Tries';
     }
     ##
     ## Build the menu
@@ -270,10 +1145,11 @@ sub CreateInterface {
     $Str .= '<tr>';
     $Str .= '<td align="center"><b>'.&mt('Sections').'</b></td>';
     $Str .= '<td align="center"><b>'.&mt('Enrollment Status').'</b></td>';
-    $Str .= '<td align="center"><b>'.&mt('Sequences and Folders').'</b></td>';
-    $Str .= '<td align="center"><b>'.&mt('Analyze By').'</b></td>';
+#    $Str .= '<td align="center"><b>'.&mt('Sequences and Folders').'</b></td>';
+    $Str .= '<td align="center">&nbsp;</td>';
     $Str .= '</tr>'."\n";
-    #
+    ##
+    ## 
     $Str .= '<tr><td align="center">'."\n";
     $Str .= &Apache::lonstatistics::SectionSelect('Section','multiple',5);
     $Str .= '</td>';
@@ -282,7 +1158,7 @@ sub CreateInterface {
     $Str .= &Apache::lonhtmlcommon::StatusOptions(undef,undef,5);
     $Str .= '</td>';
     #
-    $Str .= '<td align="center">';
+#    $Str .= '<td align="center">';
     my $only_seq_with_assessments = sub { 
         my $s=shift;
         if ($s->{'num_assess'} < 1) { 
@@ -291,32 +1167,64 @@ sub CreateInterface {
             return 1;
         }
     };
-    $Str .= &Apache::lonstatistics::MapSelect('Maps','multiple,all',5,
+    &Apache::lonstatistics::MapSelect('Maps','multiple,all',5,
                                               $only_seq_with_assessments);
-    $Str .= '</td>';
-    #
+    ##
+    ##
     $Str .= '<td>';
-    $Str .='<input type="radio" name="AnalyzeBy" value="Tries" ';
-    if ($ENV{'form.AnalyzeBy'} eq 'Tries') {
-        $Str .= 'checked ';
-    }
-    $Str .= '>'.&mt('Tries').'<br />';
-    $Str .='<input type="radio" name="AnalyzeBy" value="Time" ';
-    if ($ENV{'form.AnalyzeBy'} eq 'Time') {
-        $Str .= 'checked ';
+    { # These braces are here to organize the code, not scope it.
+        {
+            $Str .= '<nobr>'.&mt('Analyze Over ');
+            $Str .='<select name="AnalyzeOver" >';
+            $Str .= '<option value="Tries" ';
+            if (! exists($ENV{'form.AnalyzeOver'}) || 
+                $ENV{'form.AnalyzeOver'} eq 'Tries'){
+                # Default to Tries
+                $Str .= ' selected ';
+            }
+            $Str .= '>'.&mt('Tries').'</option>';
+            $Str .= '<option value="Time" ';
+            $Str .= ' selected ' if ($ENV{'form.AnalyzeOver'} eq 'Time');
+            $Str .= '>'.&mt('Time').'</option>';
+            $Str .= '</select></nobr><br />';
+        }
+        {
+            $Str .= '<nobr>'.&mt('Analyze as ');
+            $Str .='<select name="AnalyzeAs" >';
+            $Str .= '<option value="Concepts" ';
+            if (! exists($ENV{'form.AnalyzeAs'}) || 
+                $ENV{'form.AnalyzeAs'} eq 'Concepts'){
+                # Default to Concepts
+                $Str .= ' selected ';
+            }
+            $Str .= '>'.&mt('Concepts').'</option>';
+            $Str .= '<option value="Foils" ';
+            $Str .= ' selected ' if ($ENV{'form.AnalyzeAs'} eq 'Foils');
+            $Str .= '>'.&mt('Foils').'</option>';
+            $Str .= '</select></nobr><br />';
+        }
+        {
+            $Str .= '<br /><nobr>'.&mt('Number of Plots:');
+            $Str .= '<select name="NumPlots">';
+            if (! exists($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) {
+                $Str .= '<option value="'.$i.'" ';
+                if ($ENV{'form.NumPlots'} == $i) { $Str.=' selected '; }
+                $Str .= '>'.$i.'</option>';
+            }
+            $Str .= '</select></nobr>';
+        }
     }
-    $Str .= '>'.&mt('Time').'<br />';
     $Str .= '</td>';
-    #
+    ##
+    ##
     $Str .= '</tr>'."\n";
     $Str .= '</table>'."\n";
-    $Str .= '<input type="submit" name="ProblemAnalysis" value="'.
-        &mt('Analyze Problem').'" />';
-    $Str .= '&nbsp;'x5;
-    $Str .= '<input type="submit" name="ClearCache" value="'.
-        &mt('Clear Caches').'" />';
-    $Str .= '&nbsp;'x5;
-    return ($Str);
+    return $Str;
 }
 
 sub OptionResponseProblemSelector {
@@ -326,7 +1234,6 @@ sub OptionResponseProblemSelector {
         next if ($seq->{'num_assess'}<1);
         my $seq_str = '';
         foreach my $res (@{$seq->{'contents'}}) {
-#            &Apache::lonnet::logthis('checking '.$res->{'title'});
             next if ($res->{'type'} ne 'assessment');
             foreach my $part (@{$res->{'parts'}}) {
                 my $partdata = $res->{'partdata'}->{$part};
@@ -364,6 +1271,19 @@ sub OptionResponseProblemSelector {
     return $Str;
 }
 
+#########################################################
+#########################################################
+##
+##              Misc functions
+##
+#########################################################
+#########################################################
+sub get_problem_symb {
+    my $problemstring = shift();
+    my ($symb,$partid,$resid) = ($problemstring=~ /^(.*):([^:]*):([^:]*)$/);
+    return ($symb,$partid,$resid);
+}
+
 sub get_resource_from_symb {
     my ($symb) = @_;
     foreach my $seq (&Apache::lonstatistics::Sequences_with_Assess()) {
@@ -376,20 +1296,58 @@ sub get_resource_from_symb {
     return undef;
 }
 
+sub get_time_from_row {
+    my ($row) = @_;
+    if (ref($row)) {
+        return $row->[3];
+    } 
+    return undef;
+}
+
+sub get_tries_from_row {
+    my ($row) = @_;
+    if (ref($row)) {
+        return $row->[5];
+    }
+    return undef;
+}
+
+sub Process_Row {
+    my ($row) = @_;
+    my %RowData;
+    my ($student_id,$award,$grading,$submission,$time,$tries) = @$row;
+    return undef if ($award eq 'MISSING_ANSWER');
+    if ($award =~ /(APPROX_ANS|EXACT_ANS)/) {
+        $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]);
+        my (undef,$submission) = split('=',$Foilsubs[$j]);
+        if ($correct) {
+            $RowData{$foilid}->{'_correct'}++;
+        } else {
+            $submission = &Apache::lonnet::unescape($submission);
+            $RowData{$foilid}->{$submission}++;
+        }
+        $RowData{$foilid}->{'_total'}++;
+    }
+    return %RowData;
+}
+
+##
+## get problem data and put it into a useful data structure.
+## note: we must force each foil and option to not begin or end with
+##       spaces as they are stored without such data.
+##
 sub get_problem_data {
     my ($url) = @_;
-#    my $Answ=&Apache::lonnet::ssi($URI,('grade_target' => 'analyze',
-#                                  'grade_username' => $sname,
-#                                  'grade_domain' => $sdom,
-#                                  'grade_courseid' => $cid,
-#                                  'grade_symb' => $symb));
     my $Answ=&Apache::lonnet::ssi($url,('grade_target' => 'analyze'));
     (my $garbage,$Answ)=split(/_HASH_REF__/,$Answ,2);
     my %Answer;
     %Answer=&Apache::lonnet::str2hash($Answ);
-#    &Apache::lonnet::logthis('keys of %Answer = '.join(', ',(keys(%Answer))));
-#    &Apache::lonnet::logthis('$Answer{parts} = '.
-#                             join(', ',@{$Answer{'parts'}}));
     my %Partdata;
     foreach my $part (@{$Answer{'parts'}}) {
         while (my($key,$value) = each(%Answer)) {
@@ -403,45 +1361,23 @@ sub get_problem_data {
                 } elsif ($key =~ /^concept\.(.*)$/) {
                     my $concept = $1;
                     foreach my $foil (@$value) {
-                        $Partdata{$part}->{$foil}->{'Concept'}=$concept;
+                        $Partdata{$part}->{'Foils'}->{$foil}->{'Concept'}=
+                                                                      $concept;
                     }
                 }
- #               &Apache::lonnet::logthis($part.' '.$key.' (array) = '.
- #                                        join(', ',@$value));
             } else {
-                $value =~ s/^\s*//g;
-                $value =~ s/\s*$//g;
                 if ($key=~ /^foil\.text\.(.*)$/) {
                     my $foil = $1;
-                    $Partdata{$part}->{'Foiltext'}->{$foil}=$value;
+                    $Partdata{$part}->{'Foils'}->{$foil}->{'name'}=$foil;
+                    $value =~ s/(\s*$|^\s*)//g;
+                    $Partdata{$part}->{'Foils'}->{$foil}->{'text'}=$value;
                 } elsif ($key =~ /^foil\.value\.(.*)$/) {
                     my $foil = $1;
-                    $Partdata{$part}->{'FoilValues'}->{$foil}=$value;
+                    $Partdata{$part}->{'Foils'}->{$foil}->{'value'}=$value;
                 }
-#                &Apache::lonnet::logthis($part.' '.$key.' = '.$value);
             }
         }
     }
-
-#    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 $symb;
     return %Partdata;
 }