array_column()WP-CLI 1.0

Returns the values from a single column of the input array, identified by the $columnKey.

Optionally, you may provide an $indexKey to index the values in the returned array by the values from the $indexKey column in the input array.

No Hooks.

Return

Array.

Usage

array_column( $input, $columnKey, $indexKey );
$input(array)
A multi-dimensional array (record set) from which to pull a column of values.
Default: null
$columnKey(mixed)
The column of values to return. This value may be the integer key of the column you wish to retrieve, or it may be the string key name for an associative array.
Default: null
$indexKey(mixed)
(Optional.) The column to use as the index/keys for the returned array. This value may be the integer key of the column, or it may be the string key name.
Default: null

Code of array_column() WP-CLI 2.7.0-alpha

function array_column($input = null, $columnKey = null, $indexKey = null)
{
    // Using func_get_args() in order to check for proper number of
    // parameters and trigger errors exactly as the built-in array_column()
    // does in PHP 5.5.
    $argc = func_num_args();
    $params = func_get_args();

    if ($argc < 2) {
        trigger_error("array_column() expects at least 2 parameters, {$argc} given", E_USER_WARNING);
        return null;
    }

    if (!is_array($params[0])) {
        trigger_error(
            'array_column() expects parameter 1 to be array, ' . gettype($params[0]) . ' given',
            E_USER_WARNING
        );
        return null;
    }

    if (!is_int($params[1])
        && !is_float($params[1])
        && !is_string($params[1])
        && $params[1] !== null
        && !(is_object($params[1]) && method_exists($params[1], '__toString'))
    ) {
        trigger_error('array_column(): The column key should be either a string or an integer', E_USER_WARNING);
        return false;
    }

    if (isset($params[2])
        && !is_int($params[2])
        && !is_float($params[2])
        && !is_string($params[2])
        && !(is_object($params[2]) && method_exists($params[2], '__toString'))
    ) {
        trigger_error('array_column(): The index key should be either a string or an integer', E_USER_WARNING);
        return false;
    }

    $paramsInput = $params[0];
    $paramsColumnKey = ($params[1] !== null) ? (string) $params[1] : null;

    $paramsIndexKey = null;
    if (isset($params[2])) {
        if (is_float($params[2]) || is_int($params[2])) {
            $paramsIndexKey = (int) $params[2];
        } else {
            $paramsIndexKey = (string) $params[2];
        }
    }

    $resultArray = [];

    foreach ($paramsInput as $row) {
        $key = $value = null;
        $keySet = $valueSet = false;

        if ($paramsIndexKey !== null && array_key_exists($paramsIndexKey, $row)) {
            $keySet = true;
            $key = (string) $row[$paramsIndexKey];
        }

        if ($paramsColumnKey === null) {
            $valueSet = true;
            $value = $row;
        } elseif (is_array($row) && array_key_exists($paramsColumnKey, $row)) {
            $valueSet = true;
            $value = $row[$paramsColumnKey];
        }

        if ($valueSet) {
            if ($keySet) {
                $resultArray[$key] = $value;
            } else {
                $resultArray[] = $value;
            }
        }

    }

    return $resultArray;
}