Group 2d array data by second level keys and calculate average within each group

Question

I have a two-dimensional array containing names and integer values. The rows do not consistently contain all names. I need to group the data by name and find the average of all values in each group.

Sample array:

$games = [
    [
        "Armstrong_Tony" => 7,
        "Blair_Jarryd" => 7,
        "Broomhead_Tim" => 11
    ],
    [
        "Armstrong_Tony" => 19,
        "Ball_Luke" => 20,
        "Blair_Jarryd" => 20,
        "Broomhead_Tim" => 23
    ],
    [
        "Ball_Luke" => 20,
        "Beams_Dayne" => 14,
        "Blair_Jarryd" => 19,
        "Frost_Jack" => 8,
        "Goldsack_Tyson" => 7
    ]
];

Desired result:

[
  'Armstrong_Tony' => 13,
  'Blair_Jarryd' => 15.333333333333334,
  'Broomhead_Tim' => 17,
  'Ball_Luke' => 20,
  'Beams_Dayne' => 14,
  'Frost_Jack' => 8,
  'Goldsack_Tyson' => 7,
]

My coding attempt:

$arr = array_merge_recursive($games[0],$games[1],$games[2],$games[3],$games[4]);
ksort($arr);

foreach($arr as $player => $val) {

    if(array_key_exists($player, $games[0])) {
        $prev_game_0 = $games[0][$player];
    } else {
        $prev_game_0 = "";
    }
    if(array_key_exists($player, $games[1])) {
        $prev_game_1 = $games[1][$player];
    } else {
        $prev_game_1 = "";
    }
    if(array_key_exists($player, $games[2])) {
        $prev_game_2 = $games[2][$player];
    } else {
        $prev_game_2 = "";
    }
    if(array_key_exists($player, $games[3])) {
        $prev_game_3 = $games[3][$player];
    } else {
        $prev_game_3 = "";
    }
    if(array_key_exists($player, $games[4])) {
        $prev_game_4 = $games[4][$player];
    } else {
        $prev_game_4 = "";
    }

    $last_5_array[$player] = array($prev_game_0, $prev_game_1, $prev_game_2, $prev_game_3, $prev_game_4);
}

Answer 1

This should work for you to get all keys and all averages:

Here i go through each innerArray and get all key values after saving them in a array i flatter the array and only take unique values

After that i use array_column() (For PHP +5.5), count() and array_sum() to calculate the average.

<?php

    $arr = array(
                array(
                    "Armstrong_Tony" => 7,
                    "Blair_Jarryd" => 7,
                    "Broomhead_Tim" => 11
                ),
                array(
                    "Armstrong_Tony" => 19,
                    "Ball_Luke" => 20,
                    "Blair_Jarryd" => 20,
                    "Broomhead_Tim" => 23
                ),
                array(
                    "Ball_Luke" => 20,
                    "Beams_Dayne" => 14,
                    "Blair_Jarryd" => 19,
                    "Frost_Jack" => 8,
                    "Goldsack_Tyson" => 7
                )
        );

    $keys = array();
    $average = array();

    //Get Keys
    foreach($arr as $innerArray)
        $keys[] = array_keys($innerArray);

    $keys = array_unique(call_user_func_array('array_merge', $keys));


    //Get average
    foreach($keys as $key) {
        $values = array_column($arr, $key);
        $average[$key] = array_sum($values) / count($values);
    }

    print_r($average);

?>

Output:

Array
(
    [Armstrong_Tony] => 13
    [Blair_Jarryd] => 15.333333333333
    [Broomhead_Tim] => 17
    [Ball_Luke] => 20
    [Beams_Dayne] => 14
    [Frost_Jack] => 8
    [Goldsack_Tyson] => 7
)