not able to delete line after string matches in python

Question

i'm trying to remove line if doesn't match with given string, but its not happening

# !/usr/bin/python

import os
import re
import fileinput

rootdir = path

for root, subFolders, files in os.walk(rootdir):
    for file in files:
        with open(os.path.join(root, file), "r") as f:
            lines = f.readlines()
        with open(os.path.join(root, file), "w") as f:
            for line in lines:
                if line.strip("\n") != "@angular/":
                    print(line)
                    f.write(line)

line.strip() method doesn't remove line which has '@angular/'

Answer 1

You can see if something is in a sequence with the in keyword like this:

if '@angular/' not in line:
    print(line)
    f.write(line)

Answer 2

To check if one string contain another string, use the "in" keyword:

if not "@angular/" in line:
    print(line)
    f.write(line)

Answer 3

with open('scrap.txt', encoding='utf-8') as f:
    fi = f.readlines()

fi

["@angular/ sdfhdsfdslkfa;f'a\n",
 'fskfg;lsdkfd\n',
 'dfkdsjgladjgg @angular/ fpopfd;fk\n',
 'dgksgeo[p4w097642utf\n',
 '@angular/ ahafeofij[to hellljdsiohf\n',
 'afkakgAF[\n',
 '\n']

new=[]

for i in range(len(fi)):
    try:
        if re.search(r'@angular/', fi[i]).group():
            print('found in ', i)
    except AttributeError:
        for i in range(len(fi)):
    try:
        if re.search(r'@angular/', fi[i]).group():
            print('found in ', i)
    except AttributeError:
        print(f'not found in {i} so added to new:')
        new.append(fi[i])

output:
------
found in  0
not found in 1 so added to new:
found in  2
not found in 3 so added to new:
found in  4
not found in 5 so added to new:
not found in 6 so added to new:

print(new)
['fskfg;lsdkfd\n', 'dgksgeo[p4w097642utf\n', 'afkakgAF[\n', '\n']