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<?php /* @link http://stackoverflow.com/q/15931375/2261774 */ error_reporting(~0); $array = array( array('Jan 2010', 65.75), array('Jan 2010', 211.05), array('Jan 2010', 582.7), array('Feb 2010', 136.3), array('Feb 2010', 215.32), array('Feb 2010', 413.9), array('Mar 2010', 156.35), array('Mar 2010', 210.54), array('Mar 2010', 585.15), array('Apr 2010', 126.1), array('Apr 2010', 255.47), array('Apr 2010', 329.1), array('May 2010', 109), array('May 2010', 170), array('May 2010', 716.7), ); foreach($array as $key => &$entry) { list($month, $value) = $entry; if (isset($ptr[$month])) { $ptr[$month][] = $value; unset($array[$key]); } else { $ptr[$month] = &$entry; } } unset($ptr); print_r($array);

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