Get average interval between two dates PHP

Question

So I have the following array ($lifeSpanArray) and I'm looking to calculate the average interval between the two dates.

What I have so far, but I think I'm thinking slightly wrong with it:

<?php
    foreach ($lifeSpanArray as $key) {

        $newTimeAdd = new DateTime($key["timeAdded"]);
        $newTimeRead = new DateTime($key["timeRead"]);

        $interval = $newTimeAdd->diff($newTimeRead);
        var_dump($interval);
    }
?>

Which outputs:

Array
(
    [0] => Array
    (
        [timeAdded] => 07/15/2014
        [timeRead] => 07/15/2014
    )
    [1] => Array
    (
        [timeAdded] => 07/14/2014
        [timeRead] => 07/14/2014
    )
    [2] => Array
    (
        [timeAdded] => 07/13/2014
        [timeRead] => 07/15/2014
    )

    [3] => Array
    (
        [timeAdded] => 07/13/2014
        [timeRead] => 07/13/2014
    )

    [4] => Array
    (
        [timeAdded] => 07/12/2014
        [timeRead] => 07/12/2014
    )

    [5] => Array
    (
        [timeAdded] => 07/12/2014
        [timeRead] => 07/12/2014
    )

    [6] => Array
    (
        [timeAdded] => 07/12/2014
        [timeRead] => 07/12/2014
    )

    [7] => Array
    (
        [timeAdded] => 07/12/2014
        [timeRead] => 07/12/2014
    )

    [8] => Array
    (
        [timeAdded] => 07/12/2014
        [timeRead] => 07/12/2014
    )

    [9] => Array
    (
        [timeAdded] => 07/11/2014
        [timeRead] => 07/11/2014
    )

    [10] => Array
    (
        [timeAdded] => 07/11/2014
        [timeRead] => 07/11/2014
    )

    [11] => Array
    (
        [timeAdded] => 07/10/2014
        [timeRead] => 07/11/2014
    )

    [12] => Array
    (
        [timeAdded] => 07/10/2014
        [timeRead] => 07/10/2014
    )
)

Answer 1

Try the following:

 <?php
        $intervals = array();
        foreach ($lifeSpanArray as $key) {

            $newTimeAdd = new DateTime($key["timeAdded"]);
            $newTimeRead = new DateTime($key["timeRead"]);
            $interval = $newTimeAdd->diff($newTimeRead);
            $intervals[] = $interval->days;//get days
        }
        if(!empty($intervals))
        {
            $average = average($intervals);
        }


    function average($arr)
    {
       return array_sum($arr)/count($arr);
    }

?>