CODEWITHSUNDEEP
pythonperformance
kiasy
kiasy

Reputation: 304

Which of these two "for" statements are more efficient?

Which of the following two codes are more efficient? (time & memory).

aList = [0,1,2,3,4,5,6,7,8,9]
for num in aList:
    if (num % 2 == 0):
        aList.pop(num)

or

aList = [0,1,2,3,4,5,6,7,8,9]
for num in range(10):
    if (num % 2 == 0):
        aList.pop(num)

So basiccaly what I'm asking is which of "for num in aList:" and "for num in range(10):" are more efficient ?

Upvotes: 0

Views: 56

Answers (1)

John La Rooy
John La Rooy

Reputation: 304137

Even if your loop did work, pop is O(n) so makes your loop very inefficient. It's nearly always better to make a new filtered list and copy that back over

aList = [0,1,2,3,4,5,6,7,8,9]
aList[:] = [n for n in aList if n % 2]

Upvotes: 1

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