Python’s isalpha() seems inconsistent

Question

I was doing the Spy Message challenge and while using the isalpha() method I noticed that some numbers are removed and others aren’t, is this a problem with the method or using it incorrectly. In the attached code it uses two examples from the challenge where the first one works correctly and the second doesn’t.

https://code.sololearn.com/cOl1ACV6GiYz/?ref=app

Edit: Ipang is completely right an shouldn’t do this if it’s possible to avoid it, however I did it anyways and got it to work, solved in comments

Answer 1

Basically, the idea of removing item from an iterable while iterating it is a bad idea. Index no longer point to a valid item once an item had been removed from an iterable, as the size of the iterable had changed.

Your first sample won't work either had there been spaces.

You might be better off to use filter() or comprehension with condition applied to get rid of unwanted characters.

Answer 2

Adding to what Ipang said , you can use regex as well!

import re

new_msg=re.sub("[^a-z]","","".join(msg))

Answer 3

https://code.sololearn.com/c8UIvq1hB030/?ref=app

Answer 4

VenomousHamsterX Here's a possible solution:

print("".join(x for x in input() if x == " " or x.isalpha())[::-1])

# Hope this helps