How to restructure multi-dimensional array with columns as rows?

Question

Is there an efficient way to change the structure of this multidimensional array? I want to group the column values.

//$arrayBefore
[[5, 4, 10], [11, 13, 15], [32, 14, 15]];

Desired result:

//$arrayAfter
[[5, 11, 32], [4, 13, 14], [10, 15, 15]];

i dont have any solution actually. I know how to in one time action, but when i want to use it as result of a script (when input can have more arrays or elements in it). Dont even know where to start , — MMike, Jul 22 '17 at 18:24
i cant use for loop because i don't know how many arrays will be in this one and dont know how to use foreach in way i like — MMike, Jul 22 '17 at 18:30

score 1 · Answer 1 · answered Jul 22 '17 at 18:31

1

<?php

$array = [[5, 4, 10], [11, 13, 15], [32, 14, 15]];

for($i = 0; $i < count($array); $i++) {
    for ($j = 0; $j < count($array[$i]); $j++) {
        $temp[$j][] = $array[$i][$j];
    }
}
print_r($temp);

OUTPUT: http://www.phpwin.org/s/BVxAx3

answered Jul 22 '17 at 18:31

Michael Eugene Yuen

2,470
2
17
19

Alive to die - Anant · Accepted Answer · 2017-07-22T18:52:44.020

0

You can do it based on array_column():-

<?php

$array = [[5, 4, 10], [11, 13, 15], [32, 14, 15]];

$final_array = [array_column($array,0),array_column($array,1),array_column($array,2)];

print_r($final_array );

Output:-https://eval.in/836310

Note:- above code will work only for this array.

More general and considering all aspects code is using foreach():-

<?php
$array = [[5, 4, 10], [11, 13, 15], [32, 14, 15]];

$final_array = array();

foreach($array as $arr){
    foreach($arr as $key=>$value){
      $final_array[$key][]=$value;
    }
}
print_r($final_array);

Output:- https://eval.in/836313

edited Jul 22 '17 at 18:52

answered Jul 22 '17 at 18:29

Alive to die - Anant

70,531
10
51
98

Would be better off using a foreach no? – Patrick Simard Jul 22 '17 at 18:45
Now i see what i was doing wrong in my foreach before.. Thanks for your solution too! Little longer but more flexible. – MMike Jul 22 '17 at 18:51
@MMike i ave added `foreach()` solution to which is more generic .You can check that. – Alive to die - Anant Jul 22 '17 at 18:54
Looks nice :) Foreach was a little confusing to me but after analyizing your soulutions i finally got it right. Thanks! – MMike Jul 22 '17 at 19:13

score 0 · Answer 3 · answered Jul 22 '17 at 18:43

If you're unsure of the array structure, you can also use foreach. Will work for more than 3 in each arrays with out any code modification

<?
$arr = [[5, 4, 10], [11, 13, 15], [32, 14, 15]];

foreach($arr as $value_arr){
    $i=0;
    foreach($value_arr as $value){
        if ($value){
            $arr2[$i][]=$value;
            $i++;
        }
    }

}

echo "<pre>";
print_r($arr2);
echo "</pre>";
?>

Array
(
    [0] => Array
        (
            [0] => 5
            [1] => 11
            [2] => 32
        )

    [1] => Array
        (
            [0] => 4
            [1] => 13
            [2] => 14
        )

    [2] => Array
        (
            [0] => 10
            [1] => 15
            [2] => 15
        )

)

score 0 · Answer 4 · answered Jul 22 '17 at 22:28

I've already been mocked on SO for promoting a variadic approach for this kind of question, but I think it is important to show what the clever developers of php have afforded coders to do.

The ... (splat operator) tells array_map() that a multi-dimensional (with a potentially variable number of subarrays) array is coming. The function then synchronously iterates each individual subarray.

In the following code, I have commented out a method that statically names the arguments $v1,$v2,$v3 used by array_map(). This will work for the OP's case.

The line of code following the commented one, is a method that dynamically accesses the values without needing to do any variable naming. This will also be hugely flexible for any case where the structure of the multi-dimensional array changes its size/shape.

PHP Manual references:

One-liner (requires PHP5.6+): (Demo with additional examples/considerations)

$m_array=[[5, 4, 10], [11, 13, 15], [32, 14, 15]];
//$new=array_map(function($v1,$v2,$v3){return [$v1,$v2,$v3];},...$m_array);
$new=array_map(function(){return func_get_args();},...$m_array);
var_export($new);

Output:

array (
  0 => 
  array (
    0 => 5,
    1 => 11,
    2 => 32,
  ),
  1 => 
  array (
    0 => 4,
    1 => 13,
    2 => 14,
  ),
  2 => 
  array (
    0 => 10,
    1 => 15,
    2 => 15,
  ),
)

...It would be cool if `$new=array_map('func_get_args',...$m_array);` would work the same way, but `func_get_args()` cannot be called dynamically, so false results and Warnings are generated. — mickmackusa, Jul 22 '17 at 22:44

How to restructure multi-dimensional array with columns as rows?

4 Answers4

Linked