keydelete(Key, N, TupleList1) -> TupleList2
内部实现:
-spec keydelete(Key, N, TupleList1) -> TupleList2 when
Key :: term(),
N :: pos_integer(),
TupleList1 :: [Tuple],
TupleList2 :: [Tuple],
Tuple :: tuple().
keydelete(K, N, L) when is_integer(N), N > 0 ->
keydelete3(K, N, L).
keydelete3(Key, N, [H|T]) when element(N, H) == Key -> T;
keydelete3(Key, N, [H|T]) ->
[H|keydelete3(Key, N, T)];
keydelete3(_, _, []) -> [].
从元组列表 TupleList1 里删除元组的第 N 个值跟 Key 是一样的元素,只删除第一个匹配的元素,后面有相同的不做处理, 最后返回处理过的新列表 TupleList2
TupleList = [{a, 1}, {b, 2}, {c, 3}, {d, 4}],
lists:keydelete(b, 1, TupleList).