Python unpacking operator (*)

by

This is Iterable Unpacking. You may have seen it in other places to assign values to multiple variables from a single expression

a, b, c = [1, 2, 3]

This syntax includes a * to indicate that this variable should be a list containing the elements from the iterable that weren’t explicitly assigned to another variable.

a, *b, c = [1, 2, 3, 4, 5]
print(b)
# [2, 3, 4]

So, what’s going on in your example? There’s only a single variable name being assigned to, so it’s going to take all the items not assigned to another variable, which in this case is all of them. If you try just

*s="abcde"

you’ll get 

SyntaxError: starred assignment target must be in a list or tuple

Which is why that comma is there, as a trailing comma is how you indicate a single-value tuple.

More Related Contents:

  1. What is the ‘@=’ symbol for in Python?
  2. ‘is’ operator behaves differently when comparing strings with spaces
  3. Why is exponentiation applied right to left?
  4. How to handle special cases in my Python code?
  5. How to select random key with common values?
  6. max() functions with string argument
  7. TypeError: Missing 1 required positional argument: ‘self’
  8. pygame.event.get() not returning any events when inside a thread
  9. Integer division in Python 2 and Python 3
  10. pythonw.exe or python.exe?
  11. Matplotlib: Specify format of floats for tick labels
  12. “x not in y” or “not x in y”
  13. Can I install Python 3.x and 2.x on the same Windows computer?
  14. Cleanest way to get last item from Python iterator
  15. How to use type hints in python 3.6?
  16. What does “ mean in Python?
  17. Generic[T] base class – how to get type of T from within instance?
  18. floating point in python gives a wrong answer [duplicate]
  19. Function chaining in Python
  20. Selenium gives “selenium.common.exceptions.WebDriverException: Message: unknown error: cannot find Chrome binary” on Mac
  21. Can someone explain this: 0.2 + 0.1 = 0.30000000000000004? [duplicate]
  22. Call a function defined in another function
  23. How to run a http server which serves a specific path?
  24. Python map object is not subscriptable [duplicate]
  25. Print without b’ prefix for bytes in Python 3
  26. How to fix “no module named ‘app_one'”
  27. Hex string to signed int in Python
  28. Python 3 bytes formatting
  29. Same name for classmethod and instancemethod
  30. How to calculate length of string in pixels for specific font and size?

Leave a Comment