How to create a tuple when i would have made a list

When creating tuples of elements you can use the same syntax as lists, except with ()s instead of []s. e.g. (1, 2, 3) instead of [1, 2, 3]. tuple([1, 2, 3]) creates a list, then builds a tuple out of the elements in that list and discards the list, which is a bunch of extra wasteful work. This includes empty tuples empty_tuple = ().

The one confusing caveat to this is tuple comprehension. Whereas for a list you can do [x * 2 for x in range(5)] to build the list [0, 2, 4, 6, 8], if you used parenthesis it doesn’t make a tuple, but a lazy-evaluated generator, which is typically not want. So that’s the case where you would use tuple(x * 2 for x in range(5)).

>>> [x * 2 for x in range(5)]
[0, 2, 4, 6, 8]
>>> tuple(x * 2 for x in range(5))
(0, 2, 4, 6, 8)
>>> (x * 2 for x in range(5))
<generator object <genexpr> at 0x7fc41fbff9f0>