Conditionally count values in array of arrays PHP

Question

I have an array of arrays like this:

array('0'=> 
            array(
           'fromDate' =>2007,
           'toDate' => 2008,
           'value' => 7)
      '1'=>
            array(
            'fromDate' =>2010,
            'toDate' => ,
            'value' => 3)
      '2'=>
            array(
            'fromDate' => 2007,
            'toDate' => ,  
            'value' => 4))

I want to count 'value', add them up grouped by 'fromDate' like this:

array('0' =>
             array(
             'fromDate' => 2007,
             'sum' => 2)
      '1' =>
            array(
            'fromDate' => 2010,
            'sum' => 1))

Any help is much appreciated!

Can you be a bit more specific about what your requirement is ? — Romi Halasz
– Romi Halasz, Commented Apr 8, 2013 at 9:20

Mark Baker · Accepted Answer · 2013-04-08 09:39:18Z

2

$myData = array('0'=>
            array(
           'fromDate' =>2007,
           'toDate' => 2008,
           'value' => 7),
      '1'=>
            array(
            'fromDate' =>2010,
            'toDate' => NULL,
            'value' => 3),
      '2'=>
            array(
            'fromDate' => 2007,
            'toDate' => NULL,
            'value' => 4)
);

$counts = array_reduce(
    $myData,
    function ($counter, $entry) {
        if (!isset($counter[$entry['fromDate']])) {
            $counter[$entry['fromDate']] = array(
                'fromDate' => $entry['fromDate'],
                'sum' => 1
            );
        } else {
            $counter[$entry['fromDate']]['sum']++;
        }
        return $counter;
    },
    array()
);

var_dump($counts);

answered Apr 8, 2013 at 9:39

Mark Baker

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3 Comments

Ja͢ck Over a year ago

+1. Not a fan of array_reduce() but this answer makes good use of it :)

Florian Lucke Over a year ago

Thanks @Mark Baker! Now I need to understand why it works like a charm :) Any tips on where to best learn everything regarding arrays?

Mark Baker Over a year ago

Best place to start (as always) is the php docs for array functions (php.net/manual/en/book.array.php); and the relevant pages on closures (php.net/manual/en/functions.anonymous.php) for using closures in callbacks

Sergei Gorjunov · Accepted Answer · 2013-04-08 09:42:16Z

1

If you want to count how many arrays with "fromDate" e.g. 2007 you have:

function countByFromDate($array) {
  $result = array();
  foreach($array as $item) {
    $fromDate = $item['fromDate'];
    if (!isset($result[$fromDate])) {
      $result[$fromDate] = array('fromDate' => $fromDate, 'sum' => 0);  
    }
    $result[$fromDate]['sum']++;
  }

  return $result; 
}

answered Apr 8, 2013 at 9:42

Sergei Gorjunov

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