function hotpot_strings($ids)
{
// array of ids of empty strings
static $HOTPOT_EMPTYSTRINGS;
if (!isset($HOTPOT_EMPTYSTRINGS)) {
// first time only
// get ids of empty strings
$emptystrings = get_records_select('hotpot_strings', 'LENGTH(TRIM(string))=0');
$HOTPOT_EMPTYSTRINGS = empty($emptystrings) ? array() : array_keys($emptystrings);
}
$strings = array();
if (!empty($ids)) {
$ids = explode(',', $ids);
foreach ($ids as $id) {
if (!in_array($id, $HOTPOT_EMPTYSTRINGS)) {
$strings[] = hotpot_string($id);
}
}
}
return implode(',', $strings);
}
function create_analysis_table(&$users, &$attempts, &$questions, &$options, &$tables)
{
$is_html = $options['reportformat'] == 'htm';
// the fields we are interested in, in the order we want them
$fields = array('correct', 'wrong', 'ignored', 'hints', 'clues', 'checks', 'weighting');
$string_fields = array('correct', 'wrong', 'ignored');
$q = array();
// statistics about the $q(uestions)
$f = array();
// statistics about the $f(ields)
////////////////////////////////////////////
// compile the statistics about the questions
////////////////////////////////////////////
foreach ($questions as $id => $question) {
// extract scores for attempts at this question
$scores = array();
foreach ($question->attempts as $attempt) {
$scores[] = $attempt->score;
}
// sort scores values (in ascending order)
asort($scores);
// get the borderline high and low scores
$count = count($scores);
switch ($count) {
case 0:
$lo_score = 0;
$hi_score = 0;
break;
case 1:
$lo_score = 0;
$hi_score = $scores[0];
break;
default:
$lo_score = $scores[round($count * 1 / 3)];
$hi_score = $scores[round($count * 2 / 3)];
break;
}
// get statistics for each attempt which includes this question
foreach ($question->attempts as $attempt) {
$is_hi_score = $attempt->score >= $hi_score;
$is_lo_score = $attempt->score < $lo_score;
// reference to the response to the current question
$response =& $attempt->responses[$id];
// update statistics for fields in this response
foreach ($fields as $field) {
if (!isset($q[$id])) {
$q[$id] = array();
}
if (!isset($f[$field])) {
$f[$field] = array('count' => 0);
}
if (!isset($q[$id][$field])) {
$q[$id][$field] = array('count' => 0);
}
$values = explode(',', $response->{$field});
$values = array_unique($values);
foreach ($values as $value) {
// $value should be an integer (string_id or count)
if (is_numeric($value)) {
$f[$field]['count']++;
if (!isset($q[$id][$field][$value])) {
$q[$id][$field][$value] = 0;
}
$q[$id][$field]['count']++;
$q[$id][$field][$value]++;
}
}
}
// end foreach $field
// initialize counters for this question, if necessary
if (!isset($q[$id]['count'])) {
$q[$id]['count'] = array('hi' => 0, 'lo' => 0, 'correct' => 0, 'total' => 0, 'sum' => 0);
}
// increment counters
$q[$id]['count']['sum'] += $response->score;
$q[$id]['count']['total']++;
if ($response->score == 100) {
$q[$id]['count']['correct']++;
if ($is_hi_score) {
$q[$id]['count']['hi']++;
} else {
if ($is_lo_score) {
$q[$id]['count']['lo']++;
}
}
}
}
// end foreach attempt
}
// end foreach question
// check we have some details
if (count($q)) {
$showhideid = 'showhide';
// shortcuts for html tags
$bold_start = $is_html ? '<strong>' : "";
$bold_end = $is_html ? '</strong>' : "";
$div_start = $is_html ? '<div id="' . $showhideid . '">' : "";
$div_end = $is_html ? '</div>' : "";
$font_red = $is_html ? '<font color="red" size="-2">' : '';
$font_blue = $is_html ? '<font color="blue" size="-2">' : '';
$font_green = $is_html ? '<font color="green" size="-2">' : '';
$font_brown = $is_html ? '<font color="brown" size="-2">' : '';
$font_end = $is_html ? '</font>' . "\n" : '';
$br = $is_html ? '<br />' : "\n";
$space = $is_html ? ' ' : "";
$no_value = $is_html ? '--' : "";
$help_button = $is_html ? helpbutton("discrimination", "", "quiz", true, false, "", true) : "";
// table properties
unset($table);
$table->border = 1;
$table->width = '100%';
$table->caption = get_string('itemanal', 'quiz');
if ($is_html) {
$table->caption .= helpbutton('analysistable', $table->caption, 'hotpot', true, false, '', true);
}
// initialize legend, if necessary
if (!empty($options['reportshowlegend'])) {
if (empty($tables) || empty($tables[0]->legend)) {
$table->legend = array();
} else {
$table->legend = $tables[0]->legend;
unset($tables[0]->legend);
}
}
// headings for name, attempt number and score/grade
$table->head = array($space);
$table->align = array('right');
$table->size = array(80);
// question headings
$this->add_question_headings($questions, $table, 'left', 0);
// initialize statistics
$table->stat = array();
$table->statheadercols = array(0);
// add headings for the $foot of the $table
$table->foot = array();
$table->foot[0] = array(get_string('average', 'hotpot'));
$table->foot[1] = array(get_string('percentcorrect', 'quiz'));
$table->foot[2] = array(get_string('discrimination', 'quiz') . $help_button);
// maximum discrimination index (also default the default value)
$max_d_index = 10;
////////////////////////////////////////////
// format the statistics into the $table
////////////////////////////////////////////
// add $stat(istics) and $foot of $table
$questionids = array_keys($q);
foreach ($questionids as $col => $id) {
$row = 0;
// print the question text if there is no legend
if (empty($table->legend)) {
// add button to show/hide question text
if (!isset($table->stat[0])) {
$button = $is_html ? hotpot_showhide_button($showhideid) : "";
$table->stat[0] = array(get_string('question', 'quiz') . $button);
}
// add the question name/text
$name = hotpot_get_question_name($questions[$id]);
$table->stat[$row++][$col + 1] = $div_start . $bold_start . $name . $bold_end . $div_end . $space;
}
// add details about each field
foreach ($fields as $field) {
// check this row is required
if ($f[$field]['count']) {
$values = array();
$string_type = array_search($field, $string_fields);
// get the value of each response to this field
// and the count of that value
foreach ($q[$id][$field] as $value => $count) {
if (is_numeric($value) && $count) {
if (is_numeric($string_type)) {
$value = hotpot_string($value);
$this->set_legend($table, $col, $value, $questions[$id]);
switch ($string_type) {
case 0:
// correct
$font_start = $font_red;
break;
case 1:
// wrong
$font_start = $font_blue;
break;
case 2:
// ignored
$font_start = $font_brown;
break;
}
} else {
// numeric field
$font_start = $font_green;
}
$values[] = $font_start . round(100 * $count / $q[$id]['count']['total']) . '%' . $font_end . ' ' . $value;
}
}
// end foreach $value => $count
// initialize stat(istics) row for this field, if required
if (!isset($table->stat[$row])) {
$table->stat[$row] = array(get_string($field, 'hotpot'));
}
// sort the values by frequency (using user-defined function)
usort($values, "hotpot_sort_stat_values");
// add stat(istics) values for this field
$table->stat[$row++][$col + 1] = count($values) ? implode($br, $values) : $space;
}
}
// end foreach field
// default percent correct and discrimination index for this question
$average = $no_value;
$percent = $no_value;
$d_index = $no_value;
if (isset($q[$id]['count'])) {
// average and percent correct
if ($q[$id]['count']['total']) {
$average = round($q[$id]['count']['sum'] / $q[$id]['count']['total']) . '%';
$percent = round(100 * $q[$id]['count']['correct'] / $q[$id]['count']['total']) . '%';
$percent .= ' (' . $q[$id]['count']['correct'] . '/' . $q[$id]['count']['total'] . ')';
}
// discrimination index
if ($q[$id]['count']['lo']) {
$d_index = min($max_d_index, round($q[$id]['count']['hi'] / $q[$id]['count']['lo'], 1));
} else {
$d_index = $q[$id]['count']['hi'] ? $max_d_index : 0;
}
$d_index .= ' (' . $q[$id]['count']['hi'] . '/' . $q[$id]['count']['lo'] . ')';
}
$table->foot[0][$col + 1] = $average;
$table->foot[1][$col + 1] = $percent;
$table->foot[2][$col + 1] = $d_index;
}
// end foreach $question ($col)
// add javascript to show/hide question text
if (isset($table->stat[0]) && $is_html && empty($table->legend)) {
$i = count($table->stat[0]);
$table->stat[0][$i - 1] .= hotpot_showhide_set($showhideid);
}
$tables[] =& $table;
$this->create_legend_table($tables, $table);
}
// end if (empty($q)
}
