python if command for a list

[fid]

Hi,

Please check the following code.

number = 20000

lst = [0,12500,50000,150000]

lst.append(number)
lst.sort()

for b in lst:
    if lst.index(b) > lst.index(number):
        lst.remove(b)
       
print("final list:",lst)

I am trying to append "number" to the list, then sort it in ascending order, then remove all of the numbers that are greater than "number".

Appending and sorting are fine, but, the list output is incorrect.

I have included some example outputs with their inputs below. The values that shouldn't be in the list are in bold (any number greater than "number").

number: 5000
original list: [0, 12500, 50000, 150000]
append & sorted: [0, 5000, 12500, 50000, 150000]
final list: [0, 5000, 50000]

number: 16000
original list: [0, 12500, 50000, 150000]
append & sorted: [0, 12500, 16000, 50000, 150000]
final list: [0, 12500, 16000, 150000]

number: 45000
original list: [0, 12500, 50000, 150000]
append & sorted: [0, 12500, 45000, 50000, 150000]
final list: [0, 12500, 45000, 150000]

Any numbers above the last 2 numbers in the list are fine.

FYI, I also tried removing by using the pop() function. That didn't work either.

thanks in advance

Fid

[bowlofred]

Removing elements from a list while iterating over that list isn't allowed. It confuses the iterator.

You could instead create a new list and then copy it back when done (or use itertools filterfalse()).
But in your case since you've already sorted and inserted, you could just use a slice to pull the elements you want.

lst = lst[:lst.index(b)+1]

[buran]

the problem with your code, as @bowlofred explained is that you should not remove elements from list while iterating over it.
Their suggested code however will work if b is not duplicate in the list. lst.index(number) will return the index of first occurrence of b in the list.

>>> number = 12500
>>> lst = [0, 12500, 50000, 150000]
>>> lst.append(number)
>>> lst.sort()
>>> lst = [num for num in lst if num <= number]
>>> lst
[0, 12500, 12500]

[fid]

Thank you very much for your help guys.

The code works now.

@bowlofred @buran

Fid