Using enumerate method not able to delete last item in list (python3)

Question

I am trying to iterate the list and delete the last element based on the condition. But I am getting errors.

x = [0,2,1]
for y, v in enumerate(x):
  if v is 1:  
    del x[y]

print(x)

output:

[0,2,1]

Iterating over a list and manipulating it at the same type is typically a one way road to unintended consequences such as this. — Mitchnoff, Sep 01 '22 at 16:30
also note, your code actually results in `[0, 2, 1]` but it is still probably buggy — juanpa.arrivillaga, Sep 01 '22 at 16:49

score 1 · Answer 1 · answered Sep 01 '22 at 16:39

1

It's not recommended to iterate into a list changing its elements, since you are removing the element by value you can do like this:

x = [0, 2, 1]
for i in range(x.count(1)):
    x.remove(1)

print(x)

Output

[0, 2]

answered Sep 01 '22 at 16:39

Jhones

this is a pretty inefficient approach though, funamentally polynomial time, you can do it in linear time trivially – juanpa.arrivillaga Sep 01 '22 at 16:45
i don't think time efficiency is a variable in this question btw, but nice point – Jhones Sep 01 '22 at 16:47
1

sure, but you should avoid writing inefficient code when there is an idiomatic, trivial, efficient alternative. e.g. `x = [item for item in x if item != 0]` – juanpa.arrivillaga Sep 01 '22 at 16:48
when the code efficiency isn't a deal, since the OP is a beginner clearly, list comprehension isn't the best approach – Jhones Sep 01 '22 at 16:51
You can just write the equivalent for-loop, which is perfectly pythonic and idiomatic. Absolutely, a beginner should not be shown unidiomatic, unnecessarily inefficient approaches, especially not if you don't point that out. – juanpa.arrivillaga Sep 01 '22 at 16:52

1 Answers1