What is the most pythonic way to pop a random element from a list?

by

What you seem to be up to doesn’t look very Pythonic in the first place. You shouldn’t remove stuff from the middle of a list, because lists are implemented as arrays in all Python implementations I know of, so this is an O(n) operation.

If you really need this functionality as part of an algorithm, you should check out a data structure like the blist that supports efficient deletion from the middle.

In pure Python, what you can do if you don’t need access to the remaining elements is just shuffle the list first and then iterate over it:

lst = [1,2,3]
random.shuffle(lst)
for x in lst:
  # ...

If you really need the remainder (which is a bit of a code smell, IMHO), at least you can pop() from the end of the list now (which is fast!):

while lst:
  x = lst.pop()
  # do something with the element

In general, you can often express your programs more elegantly if you use a more functional style, instead of mutating state (like you do with the list).

More Related Contents:

  1. Is there a way to ordinate numbers in a list?
  2. How can I randomly select an item from a list?
  3. Shuffling a list of objects
  4. Why does random.shuffle return None?
  5. How do you pick “x” number of unique numbers from a list in Python?
  6. Select 50 items from list at random
  7. Create random list of integers in Python
  8. Python – shuffle only some elements of a list
  9. Python: Random numbers into a list
  10. finding the biggest sequence of repeating numbers in a list
  11. How to append new line to the list
  12. Remove duplicate dict in list in Python
  13. How to efficiently compare two unordered lists (not sets) in Python?
  14. How to get a random value from dictionary?
  15. Finding max value in the second column of a nested list?
  16. list to dictionary conversion with multiple values per key?
  17. Unpacking a list / tuple of pairs into two lists / tuples
  18. Python 3 turn range to a list
  19. Call int() function on every list element?
  20. Split list into smaller lists (split in half)
  21. Find nearest indices for one array against all values in another array – Python / NumPy
  22. Splitting on last delimiter in Python string?
  23. Transform “list of tuples” into a flat list or a matrix
  24. Inserting a value into all possible locations in a list
  25. Make dictionary from list with python [duplicate]
  26. Find the index of an item in a list of lists
  27. Slicing list of lists in Python
  28. Replacing a sublist with another sublist in python
  29. Union find implementation using Python
  30. Find a value in a list [duplicate]

Leave a Comment