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Ray C
1,220 PointsWhy doesn't this code remove the list if its type is list?
messy_list = ["a", 2, 3, 1, False, [1, 2, 3]]
messy_list.insert(0, messy_list.pop(3)) for item in messy_list: if type(item) != int: messy_list.remove(item) print(messy_list)
print(messy_list) returns: [1, 2, 3, [1, 2, 3]]
2 Answers
Steven Parker
229,744 PointsAltering an iterable inside a loop that it is controlling can cause undesired behavior, such as skipping over items or using them twice.
Always use a copy of an iterable to control a loop if the loop will be making changes to it.
Vincent Cegers
1,248 PointsHa! Awesome thank you.
Vincent Cegers
1,248 PointsVincent Cegers
1,248 Pointshey, Steven sorry to bother you again. I am having this same issue even when using a copy could you help me with my code.
messy_list1 = messy_list.copy()
for x in messy_list1:
print(messy_list1)
Steven Parker
229,744 PointsSteven Parker
229,744 PointsMaking messy_list1 and using it for the loop was a good idea, but you're also removing items from it. The "remove" needs to be applied to the original "messy_list".
Steven Parker
229,744 PointsSteven Parker
229,744 PointsRay C — did this answer your question?