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Python Python Collections (Retired) Lists Redux Disemvoweled

Andrew Diodati
Andrew Diodati
3,256 Points
Posted by Andrew Diodati
Andrew Diodati
3,256 Points

Mutating Lists Over Which We Are Iterating

This question is sort-of above and beyond the topic at hand, but I would like to ask it anyway.

I have been told that it is generally bad practice to mutate a list when you are iterating over it. This is why we often see a "copy" list when we run some loops. Why, then, is it acceptable to use .remove() on state_list (given the code from the video)? Is it because of the embedded for loop - so we are technically not iterating over state_list but rather vowels instead at that exact moment?

Thank you!

1 Answer

Ricky Catron
Ricky Catron
13,023 Points
Ricky Catron
Ricky Catron
13,023 Points

I would describe it like telling a track runner to run 100 meters then as they run dig a hole at 50 meters. Suddenly boom something they expected was not there. A copy of the list can be used so the loop doesn't hit the hole but you can still remove things as needed.

What I usually do instead is add the items I would have kept to a new list.

Goodluck! --Ricky