.
// Utility functions for admin pages
require_once("../inc/util_ops.inc");
// get names of units of a given type
function units_of_type($unit, $type) {
$names = array();
if (get_class($unit) == $type) {
$names[] = $unit->name;
}
if (is_subclass_of($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 $u;
}
}
return null;
}
////// Statistics
// compute the mean and stdev of an array
//
function mean_stdev($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) |
|
";
}
function compare_bar_insuff($title, $width) {
return "
| $title |
|
";
}
function outcome_graph($x, $width) {
$n = $x[0]+$x[1]+$x[2];
if (!$n) return empty_cell();
$x0 = $width*$x[1]/$n;
$x1 = $width*$x[0]/$n;
$x2 = $width*$x[2]/$n;
if ($x[1]/$n>0.05) {
$t0 = number_format(100*$x[1]/$n)."%";
} else {
$t0 = "";
}
$s = "
";
if ($x0) {
$s .= "$t0 |
";
}
if ($x1) {
$s .= "
|
";
}
if ($x2) {
$s .= "
|
";
}
$s .= "
|
";
return $s;
}
function time_graph($t, $w) {
if ($t == 0) return "--- | ";
$x = (log10($t)+2)*$w/4;
$t = number_format($t, 1);
return "
| ";
}
function score_graph($t, $w) {
if ($t == 0) return "--- | ";
$x = $t*$w;
$y = (1-$t)*$w;
$t = number_format($t*100);
$s = "
";
if ($x) {
$s .= "$t% |
";
}
if ($y) {
$s .= " |
";
}
$s .= "
|
";
return $s;
}
function empty_cell() {
return "
| ";
}
function empty_row() {
return "
|
";
}
function bolt_style() {
echo "
";
}
?>