TopolearnTuples are how Python returns several values and represents small fixed records.
A tuple is an immutable sequence, usually written with parentheses: point = (3, 4). It's the comma that makes the tuple, not the parentheses: t = 1, 2 is a tuple, and a one-element tuple needs a trailing comma, (5,), because (5) is just the number 5 in brackets. () is the empty tuple.
You index and slice tuples like lists, but you can't append, remove or assign items. Use a tuple when the position has meaning — a coordinate, an RGB colour, a (name, age) row — and a list when you have a variable number of similar items.
Because they are immutable (and hashable, if their items are), tuples can be dictionary keys and set members: distances[("Paris", "Rome")] = 1105.
Unpacking assigns the items of any iterable to several names at once:
x, y = pointfirst, *rest = [1, 2, 3, 4]puts the leftovers in a list (rest == [2, 3, 4])for name, age in rows:unpacks each row inside the loop
Functions "return multiple values" by returning a tuple, which the caller unpacks: q, r = divmod(17, 5). When a tuple has many fields, readability suffers (row[3] says nothing); that is when collections.namedtuple, typing.NamedTuple or a dataclass become worth it.
Note that a tuple's immutability is shallow: a tuple containing a list can't be rebound to another list, but the list inside can still change.
Example
point = (3, 4)
x, y = point
print(x, y) # 3 4
single = (5,)
print(type(single), type((5))) # <class 'tuple'> <class 'int'>
def min_max(values):
return min(values), max(values) # returns a tuple
lo, hi = min_max([7, 2, 9])
print(lo, hi) # 2 9
first, *rest = [1, 2, 3, 4]
print(first, rest) # 1 [2, 3, 4]
distances = {("Paris", "Rome"): 1105}
print(distances[("Paris", "Rome")]) # 1105
rows = [("Ana", 31), ("Ben", 27)]
for name, age in rows:
print(f"{name} is {age}")Remember
- The comma makes a tuple;
(x,)is a one-element tuple - Tuples are immutable and hashable, so they work as dict keys
- Unpacking (
a, *rest = ...) works with any iterable
Watch out for
- Writing
(5)and expecting a tuple.