Note 006 The sharp array_column function

Such problems are often encountered in the work.

I get a two-dimensional array, but the array contains only the ID and name. For example, this array is like this:

$array = array (' ID ' =>a, ' name ' = ' Hy369 '), array (' ID ' =>b, ' name ' = ' PHP blog '), array (' ID ' =>c, ' name ' (= ' emlog '),);

Sometimes we need this array to get a new array like this:

Sometimes we will need this array to get a new array like this: $newArray = Array (    ' Hy369 ',    ' PHP blog ',    ' emlog ');

At this time, the general will use a foreach to dimensionality reduction. I do not know what friends are like, anyway Hy369 used to do so often.

Finally, however, I found out that the PHP5.5 version had a function specifically for that requirement: Array_column.

We just call it so we can get the results we need:

Array_column ($array, ' name ');

This function also has a more convenient function, if we pass the third argument, for example:

Array_column ($array, ' Test ', ' id ');

You will get the result:

$newArray = Array (    ' a ' => ' Hy369 ',     ' B ' => ' PHP blog ',      ' C ' => ' Emlog ',);

What do you think, anyway I was drunk, this is not the general cool AH.

However, there is a problem, I have mentioned earlier, this will be supported by the beginning of the php5.5 version.

However, the power of the people is endless, there is already a low version of the compatibility method:

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) { c8/> $result [] = $item [$column _key];            } else {                $result [$item [$index _key]] = $item [$column _key];            }            return $result;}        , []);}    }

Note, however, that the version I provide here only supports 5.3 and above, because the way in which anonymous functions, that is, function use, is supported from 5.3, and if you want to be compatible with a lower version, there is a corresponding method on the Web:

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 ($indexKey) &amp ;& Array_key_exists ($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;    }}

This is definitely a panacea, although it also uses a foreach, but independent into a function, but also more than a single time to use the foreach more convenient.

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