Laravel Collection Public API: every

every($step, $offset = 0)

The every method can be used to retrieve a subset of a collection based on each items distance from each other. It defines one required parameter $step and one optional parameter $offset.

An argument supplied for $step determines how far each item must be from each other in order to be included in the final collection. In other words, the $step is used to say "get every N-th item, where N is the $step.

An argument supplied for $offset (which is 0 by default) determines where to start when building the final collection.

The following example creates a simple collection populated with the range of numbers from 0 to 10 (there will be eleven items in the collection):

1<?php
2 
3// Create a new collection.
4$collection = collect(range(0,10));

We can retrieve all the even numbers using the every method like so:

1<?php
2 
3// Retrieve the even numbers.
4$evenNumbers = $collection->every(2);

After the code has executed, the $evenNumbers variable will hold a value similar to the following output:

 1Collection {
 2  #items: array:6 [
 3    0 => 0
 4    1 => 2
 5    2 => 4
 6    3 => 6
 7    4 => 8
 8    5 => 10
 9  ]
10}

As we can see, the returned collection contains all the even numbers from the original collection. Conversely, we can retrieve all the odd numbers just as easily:

1<?php
2 
3// Retrieve the odd numbers.
4$oddNumbers = $collection->every(2,1);

It should be noted that we had to supply an argument for the $offset parameter. So the meaning of our method call could be interpreted as "get every second item starting with the item at index 1". After the above example has executed, the $oddNumbers variable will hold a value similar to the following output:

1Collection {
2  #items: array:5 [
3    0 => 1
4    1 => 3
5    2 => 5
6    3 => 7
7    4 => 9
8  ]
9}

Here is another simple example that returns every 50th item from a collection of numbers ranging from 0 to 1000:

1<?php
2 
3// Create a new collection with a range
4// of numbers.
5$collection = collect(range(0,1000));
6 
7// Generate a subset of the collection.
8$subset = $collection->every(50);

After the code has executed, $subset would contain a value similar to the following output:

 1Collection {
 2  #items: array:21 [
 3    0  => 0
 4    1  => 50
 5    2  => 100
 6    3  => 150
 7    4  => 200
 8    5  => 250
 9    6  => 300
10    7  => 350
11    8  => 400
12    9  => 450
13    10 => 500
14    11 => 550
15    12 => 600
16    13 => 650
17    14 => 700
18    15 => 750
19    16 => 800
20    17 => 850
21    18 => 900
22    19 => 950
23    20 => 1000
24  ]
25}

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