How to group an array based on inner array keys in PHP?

Question

I have an array which consists of statistics pulled from my database. Each inner array has a key based on where it come from. I want to group all these together in a new array.

array (
  0 => 
  array (
    7 => 
    array (
      'y' => 83,
      'label' => '2019-01-04 00:00:00',
    ),
  ),
  1 => 
  array (
    7 => 
    array (
      'y' => 80,
      'label' => '2019-01-02 00:00:00',
    ),
  ),
  2 => 
  array (
    8 => 
    array (
      'y' => 50,
      'label' => '2019-01-03 00:00:00',
    ),
  ),
)

Would look like this:

array (
    0 =>
    array( 
        0 =>
        array(
            'y' => 83,
            'label' => '2019-01-04 00:00:00',
        ),
        1 =>
        array(
            'y' => 80,
            'label' => '2019-01-02 00:00:00',
        ),
    ),
    1 =>
    array(
        0 =>
        array(
            'y' => 50,
            'label' => '2019-01-03 00:00:00',
        ),
    ),
)

However, I cannot seem to use array_values() to achieve this. I want to group all of the 7's into an array and all of the 8's into an array however, I could have more numeric keys in the future.

Is there a function I can use to do this?

Why do you want the keys to become 0 for 7 and 1 for 8? Why not just keep 7 and 8? — trincot
– trincot, Commented Jan 4, 2019 at 21:24
Because I am json_encode ing the data and the graph API I am using expects no keys in the array @trincot — Jaquarh
– Jaquarh, Commented Jan 5, 2019 at 16:10

trincot · Accepted Answer · 2019-01-04 21:26:21Z

3

Assuming your input is in variable $data, you could do this:

$result = [];
foreach($data as $arr) {
    foreach($arr as $k => $v) {
        $result[$k][] = $v;
    }
}

This will maintain the original inner-key value, so for your example input the result will have keys 7 and 8, not 0 and 1.

If you want that, then do one thing extra:

$result = array_values($result);

answered Jan 4, 2019 at 21:26

trincot

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2 Comments

Jaquarh Over a year ago

You, my friend, are my hero! Thank you so much! I'll accept when I can - this worked so perfectly and has saved me another n hours of frustration!

trincot Over a year ago

@rev, indeed, but I found the OP's "...I could have more numeric keys..." open for interpretation so I thought "better be safe than sorry".

Brogan · Accepted Answer · 2019-01-04 21:34:50Z

0

Give this a try!

<?php
$array = 
array(
    0 => array (
        7 => array (
            'y' => 83,
            'label' => '2019-01-04 00:00:00'
        )
    ),
    1 => array (
        7 => array (
            'y' => 80,
            'label' => '2019-01-02 00:00:00'
        )
    ),
    2 => array (
        8 => array (
            'y' => 50,
            'label' => '2019-01-03 00:00:00'
        )
    )
);

$sorted = array();
foreach($array as $key => $value)
    $sorted[key($value)][] = $array[$key][key($value)];

print_r($sorted);

answered Jan 4, 2019 at 21:34

Brogan

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