How to convert php array into a collection

In PHP development, we often need to convert arrays into sets (also called lists or sequences) to make it easier to perform a series of operations. A collection is a data structure used to store and manipulate sequences of elements, often used to filter, sort, filter, and map data. PHP's built-in array function provides many useful functions to convert and operate between arrays and collections.

This article will introduce how to convert an array to a collection in PHP and provide some common operation examples.

1. Convert an array to a collection

In PHP, you can use the array_values ​​function of the built-in array function to convert an associative array containing key-value pairs into an indexed array. Each element of an indexed array is an array containing a key and a value.

Here is some sample code that demonstrates how to convert an associative array to an indexed array:

$fruits = array(
    'apple' => 'red',
    'banana' => 'yellow',
    'grape' => 'purple'
);

// Use array_values function to convert the associative array to an indexed array
$fruits_list = array_values($fruits);

print_r($fruits_list);

This will output the following results:

Array
(
    [0] => red
    [1] => yellow
    [2] => purple
)

Now, we have successfully converted an associative array Convert to indexed array. We can continue to use this array for subsequent operations.

2. Common operations on collections

Once we convert the array into a collection, we can use PHP's array function to perform a series of common collection operations. The following are some common operations:

2.1. Traversing the collection

You can use a loop to traverse all elements in the collection. For example, the following code will iterate through each element in the collection and print them:

$fruits = array('apple', 'banana', 'grape');

foreach($fruits as $fruit) {
    echo $fruit . "\n";
}

This will output the following results:

apple
banana
grape

2.2. Filtering the collection

You can use array_filter Function to filter elements in a collection. The array_filter function accepts a callback function as a parameter, which will determine which elements should be retained in the result collection. For example, the following code will filter out all elements whose string length is greater than or equal to 6:

$fruits = array('apple', 'banana', 'grape', 'kiwi', 'lemon');

$filtered_fruits = array_filter($fruits, function($fruit) {
    return strlen($fruit) >= 6;
});

print_r($filtered_fruits);

This will output the following results:

Array
(
    [1] => banana
    [2] => grape
    [4] => lemon
)

2.3. Mapping collection

You can use array_map Function to map each element in the collection to a new value. The array_map function also accepts a callback function as a parameter, which will return a new value based on each element in the collection. For example, the following code will convert each element in the collection to uppercase letters:

$fruits = array('apple', 'banana', 'grape');

$mapped_fruits = array_map(function($fruit) {
    return strtoupper($fruit);
}, $fruits);

print_r($mapped_fruits);

This will output the following results:

Array
(
    [0] => APPLE
    [1] => BANANA
    [2] => GRAPE
)

2.4. Folding the collection

You can use array_reduce Function to collapse each element in a collection and combine it into a single value. The array_reduce function accepts a callback function as a parameter. The callback function will accept two parameters: the value of the previous element and the value of the current element, and return their combined value. For example, the following code will calculate the sum of all elements in the set:

$numbers = array(1, 2, 3, 4, 5);

$total = array_reduce($numbers, function($prev, $current) {
    return $prev + $current;
}, 0);

echo $total;

This will output the following result:

15

3. Summary

In PHP, We can easily convert an array into a collection using the built-in array function. Once we convert an array into a collection, we can use a range of useful collection operations such as filtering, mapping, folding, etc. By mastering these technologies, data can be manipulated and managed more easily.

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