removing an item from a list of strings

Question

I have a list of strings stored in a variable pdf paths, and I have another list of strings that if any item in my pdf paths list contains, it should be removed.

It works for some strings but not for others even though the string contain the same word.

def remove_derivaties(blacklist, pdf_list):
    for x in blacklist:
        for y in pdf_list:
            if x in y:
                pdf_list.remove(y)
    return pdf_list


def main():
    string = ["P:\\Example Files\\Latest\\PRM-FRM-011 Calc Review Form.pdf",
              "P:\\Example Files\\Latest\\PRM-FRM-003 Project Assignment Form.pdf",
              "control_string"]

    exclude = ["P:\\Example Files",
               "control_string1"]

    not_excluded = remove_derivaties(exclude, string)
    print(not_excluded)

The output is ['P:\\Example Files\\Latest\\PRM-FRM-003 Project Assignment Form.pdf', 'control_string']

yet the exclude word is contained in both strings

I am just using the pdfs path as a string and then trying to exclude those strings that contain certain keywords — liam, Mar 31 '22 at 07:51
This is the classic "modifying a list whilst iterating over it" paradigm. You can't do that (reliably) — DarkKnight, Mar 31 '22 at 07:54
You're removing from the list that you're iterating over, never do this — Sayse, Mar 31 '22 at 07:54
Don't `.remove()` from the list you are iterating over. Chances are, you mess up the iteration. Build a new list of valid items — gnight, Mar 31 '22 at 07:55
Sidebar: wasn't there an exception raised about that in the past? Was that python 2.7 or another language entirely? — gnight, Mar 31 '22 at 07:57

score 0 · Accepted Answer · answered Mar 31 '22 at 07:57

Is this the correct behaviour?

from typing import List

string = ["P:\\Example Files\\Latest\\PRM-FRM-011 Calc Review Form.pdf",
          "P:\\Example Files\\Latest\\PRM-FRM-003 Project Assignment Form.pdf",
          "control_string"]

exclude = ["P:\\Example Files",
           "control_string1"]

def substring_in_string(substring: str, string: str) -> bool:
    return substring in string

def substrings_in_string(substrings: List[str], string: str) -> List[bool]:
    return [substring_in_string(substring, string) for substring in substrings]

not_excluded = [s for s in string if not any(substrings_in_string(exclude, s))]

output:

['control_string']

removing an item from a list of strings

1 Answers1