php sum selected keys in array with unique id

Here considering the date and picture are same for each userid.

// define an empty array
 $new_array = array();

// loop the array
foreach($list as $value){
    $new_array[$value['userid']]['userid'] = $value['userid'];
    $new_array[$value['userid']]['picture'] = $value['picture'];
    // add the share values for each user
    $new_array[$value['userid']]['share'] = (isset($new_array[$value['userid']]['share'])) ? $new_array[$value['userid']]['share']+$value['share'] : $value['share'];
    $new_array[$value['userid']]['sharedate'] = $value['sharedate'];
}

print_r($new_array);

to reset the keys use array_values($new_array);

Out put:

Array
(
    [1042] => Array
        (
            [userid] => 1042
            [picture] => 7a86b24.jpg
            [share] => 63
            [sharedate] => 2017-10-02
        )

    [1007] => Array
        (
            [userid] => 1007
            [picture] => 3a83a6d.jpg
            [share] => 159
            [sharedate] => 2017-10-02
        )
)