PHP method to get a specified column in an array

This article mainly shares with you the method of obtaining a specified column in an array in PHP. For a multi-dimensional array (taking a two-dimensional array as an example), it is often necessary to obtain one of the columns. For example, there are several pieces of user data, which is a two-dimensional array. , now we need to get the names of these users, there are many ways to achieve it:

$arr = array(
	array(
		'id'=>'101',
		'name'=>'qu',
		'age'=>28
	),
	array(
		'id'=>'102',
		'name'=>'you',
		'age'=>24
	),
	array(
		'id'=>'103',
		'name'=>'zheng',
		'age'=>22
	),
	array(
		'id'=>'104',
		'name'=>'zhu',
		'age'=>23
	)
);

Method 1: Use PHP built-in function array_column() to achieve

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

Execution statement:

$result = array_column($arr,'name')；
print_r($result);

The result is as follows:

Array
(
    [0] => qu
    [1] => you
    [2] => zheng
    [3] => zhu
)

If the optional parameter index_key is specified, the value of this column in the input array will be used as the return array The key corresponding to the value in .

$result = array_column($arr,'name','id');
print_r($result);

The results are as follows:

Array
(
    [101] => qu
    [102] => you
    [103] => zheng
    [104] => zhu
)

Please use this function with caution, because this function is only valid in PHP5.5 or above.

Method 2: Use PHP built-in function array_map() to implement

array array_map ( callable $callback , array $arr1 [, array $... ] )

array_map() returns an array that contains arr1 All units after the callback has been applied. The first parameter is a callback function, and the return value is an array. Each element of the array is processed by the callback function (callback).

First declare a processing function:

function get_val($arr){
	return $arr['name'];
}

Then act on the array_map() function:

$result = array_map('get_val',$arr);
print_r($result);

The execution result is as follows:

Array
(
    [0] => qu
    [1] => you
    [2] => zheng
    [3] => zhu
)

Here array_map() The first parameter is a callback function, and it is a well-known function defined in advance. Here we can also use anonymous functions like js:

$result = array_map(function($v){
	return $v['name'];
},$arr);

The execution results are the same.

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