The preferred syntax, which is more flexible and doesn't leak the loop variable, is to use generator expressions: >>> x = ['1', '2', '3', '4', '5'] >>> y =

The preferred syntax, which is more flexible and doesn't leak the loop variable, is to use generator expressions: >>> x = ['1', '2', '3', '4', '5'] >>> y = list(int(i) for i in x) >>> y [1, 2, 3, 4, 5] It also works for tuples: >>> y = tuple(int(i) for i in x) >>> y (1, 2, 3, 4, 5) And for dicts: >>> y = dict((i, int(i)) for i in x) >>> y {'1': 1, '3': 3, '2': 2, '5': 5, '4': 4} And if you want a lazily-evaluated generator: >>> y = (int(i) for i in x) >>> y <generator object <genexpr> at 0xb7655eb4> Also, as I mentioned before, generator expressions don't leak the loop variable: >>> i = 42 >>> y = list(int(i) for i in x) >>> i 42 >>> y = [int(i) for i in x] >>> i '5' See http://www.python.org/dev/peps/pep-0289/ http://www.python.org/dev/peps/pep-0289/