filter_mapping() - remove some elements of a mapping based on a func‐ tion
mapping filter_mapping( mapping map, string fun, object ob, mixed extra, ... ); mapping map_mapping( mapping map, function f, mixed extra, ... );
Returns an mapping with the same keys as map whose items have been mapped throught 'ob->fun()' or 'f'. The function is called for each element in 'arr' and the return value is put back in that spot in after the item.
filter_array(3), sort_array(3), map(3)