How to Delete rows with Python

Question

I need a bit of help

This script will delete rows

with open("test1.txt", 'r') as f:
    lines = f.readlines()

to_delete =  ["apnid","apnzid","apncb"]
new_lines = []
for l in lines:
    for d in to_delete:
        if d in l:
            l = "",
            break
    new_lines.append(l)

with open("test2.txt", 'w') as file2:
    file2.writelines(new_lines)

I'm upgrading it to this

import os

for root, dirs, files in os.walk('Originals\.'):
    for name in files:
        nmin = os.path.join(root,name)
        with open(nmin,"r") as f:
             lines = f.readlines()
             
to_delete = ["apnid","apnzid","apncb"]
new_lines = []
for l in lines:
    for d in to_delete:
        if d in l:
            l = ""
            break
    new_lines.append(l)

with open(nmin,"w") as fout:
    fout.writelines(new_lines)

I run the Run Module and I get no error
Could you help me find where the problem

The script opens the CMD window and closes right away it doesn't delete any rows

Before 
      "apnid": -2147483648,
      "apnzid": -2147483648,
      "apncf": -2147483648,
      "apncb": -2147483648,
      "apfid": -2147483648,

Results
      "apncf": -2147483648,
      "apfid": -2147483648,

Answer 1

This will actually REMOVE the lines, rather than replace then with blanks:

import os

to_delete = ["apnid","apnzid","apncb"]

for root, dirs, files in os.walk('Originals\.'):
    for name in files:
        nmin = os.path.join(root,name)
        with open(nmin,"r") as f:
             lines = f.readlines()
             
        new_lines = []
        for l in lines:
            for d in to_delete:
                if d in l:
                    break
            else:
                new_lines.append(l)

        with open(nmin,"w") as fout:
            fout.writelines(new_lines)

Note that there is no particular reason to build the new_lines list. You could just be doing the write inside the loop.