CODEWITHSUNDEEP
python
oliver13
oliver13

Reputation: 1036

List Remove in Double loop

This is my code:

csvFile = [a,b,c,d,e,...]
brandList = [a,c,e,...]
copyFile = csvFile

for i in csvFile:
    for j in List2:
        if ' '+j.lower()+' ' in ' '+i.lower()+' ':
            print j.lower(), ' ',i.lower()
            copyFile.remove(i)

However, after removing an item, the process skips one item. So in a list of [a,b,c,d,e] removing c would skip d entirely (also the print). Be aware that I am not removing from the list I am using to loop. I also tried break. If you remove the "removal-line", print gives me the correct output.

Upvotes: 0

Views: 100

Answers (2)

Jan Hudec
Jan Hudec

Reputation: 76256

Yes, you are removing from the list you are using to loop. Because copyFile and csvFile point to the same list object. Python has purely referential semantics, so assignment makes the new variable point to the same object as the right hand expression, not a deep copy.

If you want to make a copy, construct a new list:

copyFile = list(csvFile)

Upvotes: 3

Jon Clements
Jon Clements

Reputation: 142136

What it looks like is you can use a regex with multiple conditions, and word boundaries so it only finds whole words, then use that as part of a filter to recreate a new matching list:

import re

base_items = ['a', 'b', 'c', 'the quick letter a jumped over the dog', 'eeeeee I no match...']
look_for = ['a', 'c', 'e']
rx = re.compile(r'\b({})\b'.format('|'.join(re.escape(item) for item in sorted(look_for, key=len, reverse=True))))
res = filter(rx.search, base_items)
# ['a', 'c', 'the quick letter a jumped over the dog']

Upvotes: 1

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