PHP merging subarrays

Question

So I have 2 arrays like so:

$a = array(array('1','2','3'), array('hello','darkness','my'));
$b = array(array('4','5','6'), array('old','friend','I'));

Now I want to merge the subarrays respectively:

$result = array(array_merge($a[0],$b[0]),array_merge($a[1],$b[1])));

Resulting in:

#vardump($result)
array(2) {
  [0]=>
  array(6) {
    [0]=>
    string(1) "1"
    [1]=>
    string(1) "2"
    [2]=>
    string(1) "3"
    [3]=>
    string(1) "4"
    [4]=>
    string(1) "5"
    [5]=>
    string(1) "6"
  }
  [1]=>
  array(6) {
    [0]=>
    string(5) "hello"
    [1]=>
    string(8) "darkness"
    [2]=>
    string(2) "my"
    [3]=>
    string(3) "old"
    [4]=>
    string(6) "friend"
    [5]=>
    string(1) "I"
  }
}

Well this works... but it just looks clumsy and it isn't a good solution if there would be a variable amount of subarrays I need to merge. Is there a build-in function for this kind of operation (or a more "acceptable" way to do this)?

You can just use a Foreach to do it assuming both arrays are formatted alike. — Forbs
– Forbs, Commented Jun 10, 2019 at 22:58
@Forbs yeah I thought so, but I also don't really like the look of loops ;/ — YTZ
– YTZ, Commented Jun 10, 2019 at 23:00
Loops are LIFE in php..haha...they grow and shrink depends on what you need. — Forbs
– Forbs, Commented Jun 10, 2019 at 23:09

YTZ · Accepted Answer · 2019-06-10 23:36:39Z

1

I came up with the following (with the help of @panther's answer)

function subarray_merge(...$arrays){
    $result = array();
    foreach ($arrays as $k => $v) {
        if($k === 0) {
            $result = $v;
        }else{
            foreach ($v as $ks => $vs) {
                $result[$ks] = array_merge($result[$ks], $v[$ks]);
            }
        }
    }
    return $result;
}

print_r(subarray_merge($a,$b,$c));

answered Jun 10, 2019 at 23:36

YTZ

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1 Comment

pavel Over a year ago

It's the second correct solution near wrapping array. Glad to help you!

pavel · Accepted Answer · 2019-06-10 23:24:42Z

0

Just use a foreach cycle.

<?php

$a = array(array('1','2','3'), array('hello','darkness','my'));
$b = array(array('4','5','6'), array('old','friend','I'));
$c = array(array('7','8','9'), array('old','friend','I'));

$defined_vars = get_defined_vars();

$result = [];

foreach ($defined_vars as $key => $arr) {
    if (in_array($key, ['_GET', '_POST', '_COOKIE', '_FILES', '_SESSION'])) continue;

    foreach ($arr as $k => $row) {
        if (!isset($result[$k])) {
            $result[$k] = $row;
        } else {
            foreach ($row as $r) {
                $result[$k][] = $r;
            }
        }
    }
}

echo '<pre>';
print_r($result);


--- result
Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
            [3] => 4
            [4] => 5
            [5] => 6
            [6] => 7
            [7] => 8
            [8] => 9
        )

    [1] => Array
        (
            [0] => hello
            [1] => darkness
            [2] => my
            [3] => old
            [4] => friend
            [5] => I
            [6] => old
            [7] => friend
            [8] => I
        )

)

This solution is 'hell', but working. Correct is to make wrapping array instead these variables, like

$array = [
    array(array('1','2','3'), array('hello','darkness','my')),
    array(array('4','5','6'), array('old','friend','I')),
    array(array('7','8','9'), array('old','friend','I'))
];

$result = [];

foreach ($array as $key => $arr) {
    foreach ($arr as $k => $row) {
        if (!isset($result[$k])) {
            $result[$k] = $row;
        } else {
            foreach ($row as $r) {
                $result[$k][] = $r;
            }
        }
    }
}

echo '<pre>';
print_r($result);

edited Jun 10, 2019 at 23:24

answered Jun 10, 2019 at 23:02

pavel

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3 Comments

YTZ Over a year ago

maybe I didn't clarify the question correctly, but I meant if I'd add more "subarrays", so for example adding another like this $c = array(array('7','8','9'), array('ve','come','to'));

pavel Over a year ago

@YTZ: ah, okay. Than you need to use get_defined_vars() and loop over that. But the right one solution is to make another array wrapping these vars.

YTZ Over a year ago

Okay cool. I'll accept your answer and I'll also post my own answer, where I used your pre-edited answer to fix it.

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