How Can I Efficiently Filter a PHP Array Based on a Specific Value While Preserving Keys?

How to Efficiently Filter an Array by a Specific Condition in PHP

In programming, it is often necessary to filter out specific elements from an array based on a particular condition. Here's a practical example:

Consider an array:

array("a" => 2, "b" => 4, "c" => 2, "d" => 5, "e" => 6, "f" => 2)

The goal is to filter this array and retain only those elements where the value is equal to 2. We want to maintain the original array keys.

PHP provides a built-in function called array_filter that can be used to accomplish this task. array_filter accepts two arguments: the array to be filtered and a callback function that defines the filtering condition.

In our example, we can define a callback function filterArray that takes a single argument ($value) and returns true if the value is equal to 2, and false otherwise:

function filterArray($value){
    return ($value == 2);
}

Now, we can use the array_filter function to filter the array based on the filterArray callback:

$filteredArray = array_filter($fullArray, 'filterArray');

The resulting $filteredArray will contain only those elements where the value is equal to 2:

array("a" => 2, "c" => 2, "f" => 2)

As you can see, the keys from the original array have been preserved.

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