PHP实现同array_column一样的功能

不用PHP自带的array_column函数实现同样的功能

<?php
/**
 * Created by PhpStorm.
 * User: 123456
 * Date: 2018/9/25
 * Time: 19:39
 */
 
$records = array(
    array(
        'id' => 2135,
        'first_name' => 'John',
        'last_name' => 'Doe',
    ),
    array(
        'id' => 3245,
        'first_name' => 'Sally',
        'last_name' => 'Smith',
    ),
    array(
        'id' => 5342,
        'first_name' => 'Jane',
        'last_name' => 'Jones',
    ),
    array(
        'id' => 5623,
        'first_name' => 'Peter',
        'last_name' => 'Doe',
    )
);
 
p(array_column2($records,null,'id'));
 
/**
 * 模仿array_column函数1
 * @param $arr
 * @param $column
 * @param NULL $index_key
 */
function array_column2($arr,$column,$index_key=NULL){
    if ($column && !$index_key){
        foreach ($arr as $key=>$val){
            $data[] = $val[$column];
        }
    }
    if ($index_key){
        foreach ($arr as $key=>$val){
            $data[$val[$index_key]] = $column ? $val[$column] : $val;
        }
    }
    return $data;
}
 
p(array_column3($records,null,'id'));
 
/**
 * 模仿array_column函数2
 * @param $arr
 * @param $column_key
 * @param null $index_key
 */
function array_column3($arr,$column_key,$index_key=null){
    $data = array_map(function($d) use ($column_key,$index_key){
//        p($d);
        if ($column_key && ! $index_key){
            return $d[$column_key];
        }
        if ($index_key){
            return [$d[$index_key]=>($column_key === null) ? $d : $d[$column_key]];
        }
 
    },$arr);
    $tmp=[];
    if ($index_key){
        foreach ($data as $key=>$val){
            $tmp[key($val)] = current($val);
        }
        $data = $tmp;
    }
    return $data;
}
 
function p($data){
    echo '<pre>';
    print_r($data);
    echo '</pre>';
}