PHP's method of extracting a multidimensional array of specified columns

Foreword: Sometimes in the development of this problem, we need to have a regular multidimensional array according to the vertical (column), the following methods are available:

We will take the array of polygons to deal with:

1 $arr Array (2     Array (' id ' = 1, ' name ' = ' name1 '),3     array(' id ' = 2, ' name ' = ' name2 '),4     array(' id ' = = 3, ' name ' = ' Name3 '),5     Array (' id ' = 4, ' name ' = ' name4 '),6     array(' id ' = 5, ' name ' = ' name5 '),7 );

Required results: $name _list = Array (' name1 ', ' name2 ', ' name3 ', ' name4 ', ' name5 ');

1. Using Array_column ()

PHP added a dedicated function Array_column () after version 5.5.0

Method:

1 $name _list = Array_column ($arr, ' name ');

2. Array_walk () method

Array_walk () uses a user-defined function to do callback processing for each element in the array

1 $name _list Array (); 2 Array_walk ($arrfunction($value$key use (&$name _list  ) {  3     $name _list$value[' name ']; 4 });

3. Array_map () method

The Array_map () function () is similar to Array_walk, and the callback function is acting on the cell of the given array

1 $name _list Array (); 2 Array_map (function($value use (&$name _list) {3     $ Name_list$value[' name ']; 4 $arr);

4. Foreach Loop Traversal method

The foreach () loop is slightly less efficient than the above method

1 $name _list Array (); 2 foreach ($arras$value) {3     $name _list $value [' name ']; 4 }

5. Array_map Variant

Move the beginning value of each item value of the $arr array out and get the removed value as the new array. Note that the key of the new array $name_list is still the key of the original array $arr

1 $name _list=Array_map(' Array_shift ',$arr);2 //Note: This feature gets the ID column in $arr, not the Name column. 3 In addition, you can do this if you need to get the beginning or end columns of each item in a two-dimensional array:4 5 $name _list=Array_map(' Reset ',$arr);6 $name _list=Array_map(' End ',$arr);7 8 //These three variant methods are limited in function and only useful when getting the first or last column,9 //complex arrays are difficult to work with. 

PHP's method of extracting a multidimensional array of specified columns