Laravel 5: Collapsing a Multi-Dimensional Array to a Single Level With collapse

The collapse helper method accepts an array as its only parameter. The given $array can be a single array, or a nested array. The method will then return a new array with the contents of all the nested arrays. Arrays that are collapsed can contain any data type, such as integers, string literals, objects and other arrays.

#Signature

The signature of the collapse method is:

1public static function collapse(
2    $array
3);

#Example Use

The examples that follow will use integers in all arrays. Assuming the following array and example:

 1use \Illuminate\Support\Arr;
 2 
 3$testArray = [
 4    [
 5        1,2,3,4
 6    ],
 7    [
 8        5,6,7,8,
 9    ]
10];
11 
12$collapsedArray = Arr::collapse($testArray);

The value of $collapsedArray would then be:

1array
2  0 => int 1
3  1 => int 2
4  2 => int 3
5  3 => int 4
6  4 => int 5
7  5 => int 6
8  6 => int 7
9  7 => int 8

It is important to note that the collapse method is not recursive. This can be observed in the following example:

 1use \Illuminate\Support\Arr;
 2 
 3$testArray = [
 4    [
 5        1,2,3,4
 6    ],
 7    [
 8        5,6,7,8,
 9        [
10            9,10,11,12
11        ]
12    ]
13];
14 
15$collapsedArray = Arr::collapse($testArray);

The value of $collapsedArray would then have the value:

 1array
 2  0 => int 1
 3  1 => int 2
 4  2 => int 3
 5  3 => int 4
 6  4 => int 5
 7  5 => int 6
 8  6 => int 7
 9  7 => int 8
10  8 =>
11    array
12      0 => int 9
13      1 => int 10
14      2 => int 11
15      3 => int 12

#Collapsing Collections

The collapse method will also work on collections. There is no special syntax required to use collections with the collapse method:

1use \Illuminate\Support\Arr;
2use \Illuminate\Support\Collection;
3 
4$testArray = [
5    new Collection([1,2,3,4]),
6    new Collection([5,6,7,8])
7];
8 
9$collapsedArray = Arr::collapse($testArray);

The value of $collapsedArray would then be:

1array
2  0 => int 1
3  1 => int 2
4  2 => int 3
5  3 => int 4
6  4 => int 5
7  5 => int 6
8  6 => int 7
9  7 => int 8

Nested collections can also be collapsed:

1use \Illuminate\Support\Arr;
2use \Illuminate\Support\Collection;
3 
4$testArray = new Collection([
5    new Collection([1,2,3,4]),
6    [5,6,7,8]
7]);
8 
9$collapsedArray = Arr::collapse($testArray);

The value of collapsed array would then be:

1array
2  0 => int 1
3  1 => int 2
4  2 => int 3
5  3 => int 4
6  4 => int 5
7  5 => int 6
8  6 => int 7
9  7 => int 8

#Global array_collapse Helper Function

The array_collapse function is a shortcut to calling Arr::collapse. This function is declared in the global namespace.

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