Jarrod Swift (.com)

Sorting multi-dimensional arrays

When using functions such as my simple PHP database access it is often useful to be able to sort by a field in an array (assuming you cannot use the SQL to define the order for some reason).

As an example, I have a list of 3 cars:

array( 
	  array( 'name' => 'Holden', 'colour' => 'blue' ),
	  array( 'name' => 'Honda', 'colour' => 'red'),
	  array( 'name' => 'Ford', 'colour' => 'yellow'),
);

And I want them sorted by name. I've written a simple function that uses this method.

/**
 * Sort a multi dim array by a key
 * 
 * Sorts ascending direction only
 * 
 * @return array 
 * @param $array array
 * @param $field string		The key to sort by
 */
function sort_by( $array, $field ) {
	if( !is_callable("compare_by_$field") ) {
		eval(
			"function compare_by_$field( \$x, \$y ) {
				if (\$x['$field'] == \$y['$field']) { return 0; }
			    
				return (\$x['$field'] > \$y['$field']) ? 1 : -1;
			}"	
		);
	}
	
	usort( $array, "compare_by_$field" );
	
	return $array;
}

I hope this is useful to people, feel free to use it as you see fit.

1 November 2007