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Unpacking in for

for loop

When iterating over a sequence of tuples (or of other iterables) you can unpack the items into several variables right in the for header.

Syntax

for x, y in iterable: ...
for a, b, c in iterable: ...

The count of target variables must exactly match the number of items in each tuple, or that iteration raises ValueError (not enough / too many values to unpack) — at runtime, not at parse time. When the tail length varies, a star helps: for first, *rest in ... collects the remainder into a list. Nested unpacking like for i, (x, y) in enumerate(...) needs the parentheses around the inner pair, otherwise Python expects three separate variables.

Examples

for x, y in [(1, 2), (3, 4), (5, 6)]:
    print(x + y, end=" ")  # → 3 7 11

pairs = {"a": 1, "b": 2, "c": 3}
for k, v in pairs.items():
    print(f"{k}={v}", end=" ")  # → a=1 b=2 c=3

for i, (x, y) in enumerate([(1, 2), (3, 4)]):
    print(i, x, y)  # → 0 1 2 / 1 3 4

for a, *rest in [(1, 2, 3), (4, 5, 6)]:
    print(a, rest)  # → 1 [2, 3] / 4 [5, 6]

See also

Common errors

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