Note 006 Sharp array_column function
工作中经常会遇到这样的问题。
我得到一个二维数组,但是数组当中只包含id和name。比如说这个数组是这样的:
$array = array( array('id'=>a, 'name'=>'Hy369'), array('id'=>b, 'name'=>'PHP博客'), array('id'=>c, 'name'=>'emlog'), );
有时候我们会需要通过这个数组,得到类似下面这样的新数组:
有时候我们会需要通过这个数组,得到类似下面这样的新数组: $newArray = array( 'Hy369', 'PHP博客', 'emlog', );
这时候,一般就会用一个foreach进行降维了。不知道各位朋友是怎样的,反正Hy369以前就经常这么干。
然而最后我发现,PHP5.5版本有了一个专门针对该需求的函数:array_column。
我们只需如此调用,即可得到我们需要的结果:
array_column($array, 'name');
这个函数还有个更加方便的功能,如果我们传递了第三个参数,例如:
array_column($array, 'test', 'id');
就会得到这样的结果:
$newArray = array( 'a'=>'Hy369', 'b'=>'PHP博客', 'c'=>'emlog', );
你们怎么看,反正我是醉了,这个不是一般的爽啊。
不过有个问题,我刚才已经提到,这个要php5.5版本开始才会支持。
不过,人民的力量是无穷的,已经有低版本的兼容方法了:
if (!function_exists('array_column')) { function array_column($array, $column_key, $index_key = null) { return array_reduce($array, function ($result, $item) use ($column_key, $index_key) { if (null === $index_key) { $result[] = $item[$column_key]; } else { $result[$item[$index_key]] = $item[$column_key]; } return $result; }, []); } }
不过要注意,我这里提供的版本仅支持5.3及其以上的,因为其中的匿名函数的方式,也就是function use的方式,从5.3开始被支持,如果要兼容更低的版本,网上也有对应的方法:
if (!function_exists('array_column')) { function array_column(array $array, $columnKey, $indexKey = null) { $result = array(); foreach ($array as $subArray) { if (!is_array($subArray)) { continue; } elseif (is_null($indexKey) && array_key_exists($columnKey, $subArray)) { $result[] = $subArray[$columnKey]; } elseif (array_key_exists($indexKey, $subArray)) { if (is_null($columnKey)) { $result[$subArray[$indexKey]] = $subArray; } elseif (array_key_exists($columnKey, $subArray)) { $result[$subArray[$indexKey]] = $subArray[$columnKey]; } } } return $result; } }
这个绝对是万能的方法了,虽然也用到了foreach,不过独立成了一个函数,也比每次要用的时候单独去foreach方便多了。
以上就是笔记006 犀利的array_column函数的内容,更多相关内容请关注PHP中文网(www.php.cn)!

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