Never ever modify your
list while iterating through the list.This post is taking from Indently’s shorts at https://www.youtube.com/shorts/X8KL7iAk-7k.
List Item Removal#
Suppose we want to remove an item within a list. Such as ‘B’.
And below is one of the common mistakes that junior developer makes. It uses for-loop to remove the item while iterating through the list.
But the result shows an unexpected behavior here. See the code below.
items1 = ['A', 'B', 'C', 'D', 'E']
items2 = []
for item in items1:
if item == 'B':
items1.remove('B')
else:
items2.append(item)
print(items2)
# ['A', 'D', 'E']Supposed we are expecting the result to be ['A', 'C', 'D', 'E'].
If you want to modify the original list, simply create another list.
And below here is the correct way.
items1 = ['A', 'B', 'C', 'D', 'E']
items2 = [ item for item in items1 if item != 'B' ]
print(items2)
# ['A', 'C', 'D', 'E']Links#
Indently’s YT video at 10 Nooby Mistakes Devs Often Make In Python:
