public static function general($table, $field, $mode = STAT_MODE_DIVISION, $num = 100)
{
//通用查詢格式: 對於特定資料表內單一欄位，所有資料的統計數據
//0: plot data
//1: 樣本數
//2: 極小值
//3: 極大值
//4: 均值
//5: 四分位數 array(Q1, Q2, Q3)
//6:
$data = array('data' => array(), 'samples' => null, 'min' => null, 'max' => null, 'mean' => null, 'q1' => null, 'q2' => null, 'q3' => null);
switch ($mode) {
case STAT_MODE_DIVISION:
//先辨識人數是否小於$num，小於時要特別處理
$cnt = DBC::queryOneCell('
SELECT COUNT(' . $field . ')
FROM ' . $table . '
');
if ($cnt < $num) {
$tmpdata = DBC::queryAllRow('
SELECT ' . $field . '
FROM ' . $table . '
ORDER BY ' . $field . ' ASC
');
//延展至$num個資料
$i = 0;
$step = ($cnt - 1) / $num;
do {
$index = ceil($step * $i);
$data['data'][$i] = $tmpdata[$index][0];
} while (++$i < $num);
} else {
$i = 0;
$step = $cnt / $num;
do {
$index = ceil($i * $step);
$tmpdata = DBC::queryOneCell("\n\t\t\t\t\t\t\tSELECT " . $field . "\n\t\t\t\t\t\t\tFROM " . $table . "\n\t\t\t\t\t\t\tORDER BY " . $field . " ASC\n\t\t\t\t\t\t\tLIMIT {$index}, 1\n\t\t\t\t\t\t\t");
$data['data'][$i] = $tmpdata;
} while (++$i < $num);
}
$data['samples'] = $cnt;
$stats = DBC::queryOneRow('
SELECT MIN(' . $field . '), MAX(' . $field . '), AVG(' . $field . ')
FROM ' . $table . '
');
$data['min'] = $stats[0];
$data['max'] = $stats[1];
$data['mean'] = $stats[2];
//計算四分位數 BEGIN
$q = array($data['max'] * 0.25, $data['max'] * 0.5, $data['max'] * 0.75);
for ($i = 0; $i < 3; ++$i) {
if (is_int($q[$i])) {
$data['q' . ($i + 1)] = DBC::queryOneCell('
SELECT AVG(' . $field . ')
FROM ' . $table . '
ORDER BY ' . $field . ' ASC
LIMIT ' . $q[$i] . ', 2
');
}
if (is_float($q[$i])) {
$data['q' . ($i + 1)] = DBC::queryOneCell('
SELECT ' . $field . '
FROM ' . $table . '
ORDER BY ' . $field . ' ASC
LIMIT ' . ceil($q[$i]) . ', 1
');
}
}
//計算四分位數 END
return $data;
break;
}
return null;
}
