Get array column using PHP array_column()

In PHP, sometimes we need to extract a column of data from a two-dimensional array for processing. In this case, we can use the PHP built-in function array_column(), which can easily extract a column from a two-dimensional array.

Syntax: array_column(array $input, mixed $column_key[, mixed $index_key])

Parameter description:

• $input: Array of columns to be extracted .
• $column_key: The column to be extracted, which can be a string key name or a numeric index.
• $index_key: Optional parameter. If this parameter is specified, the returned array will use the value of this parameter as the index key instead of the numeric key of the original array.

Let’s look at a practical example:

$students = array(

array('id' => 1, 'name' => 'Tom', 'score' => 80),
array('id' => 2, 'name' => 'Jack', 'score' => 90),
array('id' => 3, 'name' => 'Mary', 'score' => 85),

);

// Extract the grade column
$scores = array_column($students, 'score');
print_r($scores);

In the above code, we have a $students array containing information about 3 students. We use the array_column() function to extract the score column in the $students array, save it to the $scores array, and then use the print_r() function to output the value of the $scores array.

Run the above code, we can see the output:

Array
(

[0] => 80
[1] => 90
[2] => 85

)

You can see that there are only Contains the value of the score column in the $students array, but not the values ​​of other columns.

In addition, if we want to use id as the index key in the $scores array, we can pass in the third parameter in the array_column() function:

$students = array(

array('id' => 1, 'name' => 'Tom', 'score' => 80),
array('id' => 2, 'name' => 'Jack', 'score' => 90),
array('id' => 3, 'name' => 'Mary', 'score' => 85),

);

// Extract the score column and use id as the index key
$scores = array_column($students, 'score', 'id');
print_r($ scores);

Output result:

Array
(

[1] => 80
[2] => 90
[3] => 85

)

We can see that the score of each element in the $scores array The key is the ID of each student in the original array, and the value is the corresponding grade.

Summary:

When dealing with two-dimensional arrays, the PHP built-in function array_column() is a very practical tool. It can easily extract the target column and avoid repeatedly writing loops to find each The cumbersome operation of key values ​​greatly improves development efficiency.

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