name;
}
if (is_subclass_of($unit, "BoltSet")) {
foreach ($unit->units as $u) {
$n = units_of_type($u, $type);
$names = array_merge($names, $n);
}
}
return array_unique($names);
}
// show a menu of select units
//
function choose_select($top_unit) {
echo "";
}
// show a menu of exercise sets
//
function choose_xset($top_unit) {
echo "";
}
// Find a unit of given name
//
function lookup_unit($top_unit, $name) {
if ($top_unit->name == $name) return $top_unit;
if (is_subclass_of($top_unit, "BoltSet")) {
foreach ($top_unit->units as $child) {
$u = lookup_unit($child, $name);
if ($u) return $u;
}
}
return null;
}
////// bits of HTML for getting user info
function info_incomplete($user) {
if (!$user->bolt->birth_year) return true;
if (!$user->bolt->sex) return true;
return false;
}
function birth_year_select($user) {
$this_year = date("Y");
$x = "\n";
return $x;
}
function sex_select($user) {
$x = "\n";
return $x;
}
function request_info($user, $course) {
page_head("About you");
echo "
You may optionally tell us some facts about yourself.
This information will help us improve this course,
and will be kept private.
\n";
page_tail();
}
////// stuff related to snapshots
function compare_snapshot_filename($course_id, $select_name, $xset_name) {
return "../bolt_snap/compare_snapshot_".$course_id."_".$select_name."_".$xset_name;
}
// a "snapshot" is a condensed representation of the results
// for a particular select/xset pair.
// Namely, it's an array whose elements contain
// bolt_user: the user
// xset_result: the user's first completion of the xset
// select_finished: the user's last completion of the select before this
function write_compare_snapshot($course_id, $select_name, $xset_name, $dur) {
$now = time();
$start = $now - $dur*86400;
$xrs = BoltXsetResult::enum(
"course_id=$course_id and name='$xset_name' and create_time >= $start"
);
$sfs = BoltSelectFinished::enum(
"course_id=$course_id and name='$select_name' and end_time >= $start"
);
// make an array $a, keyed by user ID, of earliest xset result
//
$a = array();
foreach ($xrs as $xr) {
$uid = $xr->user_id;
if (!array_key_exists($uid, $a) || $xr->create_time < $a[$uid]->xr->create_time) {
$x = null;
$x->xr = $xr;
$a[$uid] = $x;
}
}
// now scan select finishes, and for each user find last one before xset
//
foreach ($sfs as $sf) {
$uid = $sf->user_id;
if (!array_key_exists($uid, $a)) {
echo "no xset result";
continue;
}
$x = $a[$uid];
$xr = $x->xr;
if ($sf->end_time > $xr->create_time) {
echo "select finish is too late";
continue;
}
if (!isset($x->sf) || $sf->create_time > $s.create_time) {
$x->sf = $sf;
$a[$uid] = $x;
}
}
// cull array elements for which we didn't find a select finish.
// Look up user records for other elements.
//
foreach ($a as $uid=>$x) {
if (!isset($x->sf)) {
unset($a[$uid]);
} else {
$user = BoincUser::lookup_id($uid);
BoltUser::lookup($user);
$x->user = $user;
$a[$uid] = $x;
}
}
$filename = compare_snapshot_filename($course_id, $select_name, $xset_name);
$f = fopen($filename, "w");
$s = null;
$s->recs = $a;
$s->dur = $dur;
$s->time = $now;
fwrite($f, serialize($s));
fclose($f);
return $s;
}
function read_compare_snapshot($course_id, $select_name, $xset_name) {
$filename = compare_snapshot_filename($course_id, $select_name, $xset_name);
$f = @fopen($filename, "r");
if (!$f) return null;
$x = fread($f, filesize($filename));
fclose($f);
return unserialize($x);
}
function map_snapshot_filename($course_id) {
return "../bolt_snap/map_snapshot_".$course_id;
}
// a "map snapshot" is:
// - an assoc array "views" mapping unit name to a list of views
// - an assoc array "results" mapping unit name to a list of results
// - an assoc array "xset_results" mapping unit name to a list of xset results
// - an assoc array "users" mapping user ID to user record
//
function write_map_snapshot($course_id, $dur) {
$now = time();
$start = $now - $dur*86400;
$views = array();
$results = array();
$xset_results = array();
$users = array();
$vs = BoltView::enum("course_id=$course_id and start_time>$start");
foreach ($vs as $v) {
if (array_key_exists($v->item_name, $views)) {
$x = $views[$v->item_name];
$x[] = $v;
$views[$v->item_name] = $x;
} else {
$views[$v->item_name] = array($v);
}
if (!array_key_exists($v->user_id, $users)) {
$user = BoincUser::lookup_id($v->user_id);
BoltUser::lookup($user);
$users[$v->user_id] = $user;
}
}
$rs = BoltResult::enum("course_id=$course_id and create_time>$start");
foreach ($rs as $r) {
if (array_key_exists($r->item_name, $results)) {
$x = $results[$r->item_name];
$x[] = $r;
$results[$r->item_name] = $x;
} else {
$results[$r->item_name] = array($r);
}
if (!array_key_exists($r->user_id, $users)) {
$user = BoincUser::lookup_id($r->user_id);
BoltUser::lookup($user);
$users[$v->user_id] = $user;
}
}
$xrs = BoltXsetResult::enum("course_id=$course_id and create_time>$start");
foreach ($xrs as $xr) {
if (array_key_exists($xr->name, $xset_results)) {
$x = $xset_results[$xr->name];
$x[] = $xr;
$xset_results[$xr->name] = $x;
} else {
$xset_results[$xr->name] = array($xr);
}
if (!array_key_exists($xr->user_id, $users)) {
$user = BoincUser::lookup_id($xr->user_id);
BoltUser::lookup($user);
$users[$v->user_id] = $user;
}
}
$y = null;
$y->views = $views;
$y->results = $results;
$y->xset_results = $xset_results;
$y->users = $users;
$y->dur = $dur;
$y->time = $now;
$filename = map_snapshot_filename($course_id);
$f = fopen($filename, "w");
fwrite($f, serialize($y));
fclose($f);
return $y;
}
function read_map_snapshot($course_id) {
$filename = map_snapshot_filename($course_id);
$f = @fopen($filename, "r");
if (!$f) return null;
$x = fread($f, filesize($filename));
fclose($f);
return unserialize($x);
}
////// Statistics
// compute the mean and stdev of an array
//
function mean_stdev($array, &$mean, &$stdev) {
$n = 0;
$m = 0;
$m2 = 0;
foreach ($array as $x) {
$n++;
$delta = $x - $m;
$m += $delta/$n;
$m2 += $delta*($x-$m);
}
$mean = $m;
$stdev = sqrt($m2/($n-1));
}
// approximate the 90% confidence interval for the mean of an array
//
function conf_int_90($array, &$lo, &$hi) {
$n = count($array);
mean_stdev($array, $mean, $stdev);
// I'm too lazy to compute the t distribution
$t_90 = 1.7;
$d = $t_90 * $stdev / sqrt($n);
$lo = $mean - $d;
$hi = $mean + $d;
}
function test_stats() {
$a = array(1,1,1,1,0,1,1,1,3, 1, 1, 1, 1);
mean_stdev($a, $mean, $stdev);
echo "mean: $mean stdev: $stdev\n";
conf_int_90($a, $lo, $hi);
echo "lo $lo hi $hi\n";
}
//////////// graph drawing
function compare_bar($title, $n, $width, $lo, $hi) {
$x1 = $width*$lo;
$x2 = $width*($hi-$lo);
$a1 = number_format($lo*100);
$a2 = number_format($hi*100);
return "
$title ($n students)
$a1
$a2
";
}
function compare_bar_insuff($title, $width) {
return "