First items in inner list efficiently as possible [duplicate]

by

This should do it:

c = [x[0] for x in A]

It’s a list comprehension that takes the first (sub-)element of every element of A.

More Related Contents:

  1. How do I profile a Python script?
  2. What is the most “pythonic” way to iterate over a list in chunks?
  3. Fastest way to check if a value exists in a list
  4. Get difference between two lists
  5. Python Sets vs Lists
  6. Are tuples more efficient than lists in Python?
  7. Flatten an irregular list of lists
  8. Replace values in list using Python [duplicate]
  9. Why is [] faster than list()?
  10. How to iterate over a list in chunks
  11. What is the time complexity of popping elements from list in Python?
  12. Python – How to check list monotonicity
  13. [] and {} vs list() and dict(), which is better?
  14. Tuple or list when using ‘in’ in an ‘if’ clause?
  15. Why is tuple faster than list in Python?
  16. Complexity of list.index(x) in Python
  17. Efficient way to take the minimum/maximum n values and indices from a matrix using NumPy
  18. Python: get a dict from a list based on something inside the dict
  19. Create random list of integers in Python
  20. Flatten an irregular (arbitrarily nested) list of lists
  21. Creating an empty list in Python
  22. Get difference between two lists with Unique Entries
  23. Is there a way to circumvent Python list.append() becoming progressively slower in a loop as the list grows?
  24. sum each value in a list of tuples
  25. Python List Indexing Efficiency
  26. Python: iterating over list vs over dict items efficiency
  27. Looking for a fast way to find the polygon a point belongs to using Shapely
  28. Which is the most efficient way to iterate through a list in python?
  29. Length of longest word in a list
  30. deque.popleft() and list.pop(0). Is there performance difference?

Leave a Comment