Remove lines that contain certain string

Question

I\'m trying to read a text from a text file, read lines, delete lines that contain specific string (in this case \'bad\' and \'naughty\'). The code I wrote goes like this:

Answer 1

to_skip = ("bad", "naughty")
out_handle = open("testout", "w")

with open("testin", "r") as handle:
    for line in handle:
        if set(line.split(" ")).intersection(to_skip):
            continue
        out_handle.write(line)
out_handle.close()

Answer 2

Use python-textops package :

from textops import *

'oldfile.txt' | cat() | grepv('bad') | tofile('newfile.txt')

Answer 3

You could simply not include the line into the new file instead of doing replace.

for line in infile :
     if 'bad' not in line and 'naughty' not in line:
            newopen.write(line)

Answer 4

bad_words = ['doc:', 'strickland:','\n']

with open('linetest.txt') as oldfile, open('linetestnew.txt', 'w') as newfile:
    for line in oldfile:
        if not any(bad_word in line for bad_word in bad_words):
            newfile.write(line)

The \n is a Unicode escape sequence for a newline.

Answer 5

The else is only connected to the last if. You want elif:

if 'bad' in line:
    pass
elif 'naughty' in line:
    pass
else:
    newopen.write(line)

Also note that I removed the line substitution, as you don't write those lines anyway.

Answer 6

Regex is a little quicker than the accepted answer (for my 23 MB test file) that I used. But there isn't a lot in it.

import re

bad_words = ['bad', 'naughty']

regex = f"^.*(:{'|'.join(bad_words)}).*\n"
subst = ""

with open('oldfile.txt') as oldfile:
    lines = oldfile.read()

result = re.sub(regex, subst, lines, re.MULTILINE) 

with open('newfile.txt', 'w') as newfile:
    newfile.write(result)