Tuples
Tuple Unpacking
Multiple assignment with tuples
Interview: Core Pythonic idiom — interviewers expect fluent unpacking usage
Tuple unpacking (also called destructuring) assigns elements of a tuple/iterable to multiple variables in a single statement. It's one of Python's most elegant features and is used pervasively in real-world code.
Basic Unpacking
- Simple:
x, y, z = (1, 2, 3) - Swap:
a, b = b, a— no temp variable needed! - From functions:
lo, hi = min_max(data) - Must match: Number of variables must match number of elements (or use *)
Extended Unpacking (Python 3)
- Star operator:
first, *rest = [1, 2, 3, 4]— first=1, rest=[2,3,4] - Middle star:
first, *middle, last = [1, 2, 3, 4]— middle captures remaining - Star collects as list: The starred variable always gets a list, even if empty
- Only one star: Can't have multiple starred variables in one unpacking
Advanced Patterns
- Ignore values: Use
_as throwaway:x, _, z = (1, 2, 3) - Nested unpacking:
(a, b), (c, d) = [(1, 2), (3, 4)] - In for loops:
for key, value in dict.items(): - Function args:
func(*args)unpacks tuple as positional arguments
Interview Tip
The swap idiom a, b = b, a is frequently asked in interviews. Under the hood, Python creates a temporary tuple on the right side (packing) and unpacks it to the left side.
Use Cases
Swapping variables without temporary storage
Extracting function return values (multiple returns)
Parallel iteration with zip and enumerate
Head/tail decomposition in recursive algorithms
Common Mistakes
Mismatching variable count and element count (raises ValueError)
Forgetting that the starred variable always gets a list (not a tuple)
Using multiple starred variables in one unpacking (SyntaxError)
Not knowing _ is just a convention — it's a valid variable name that can be reassigned