Question

I have a file that looks like this(have to put in code box so it resembles file):

text
(starts with parentheses)
         tabbed info
text
(starts with parentheses)
         tabbed info

...repeat

I want to grab only “text” lines from the file(or every fourth line) and copy them to another file. This is the code I have, but it copies everything to the new file:

import sys

def process_file(filename):

    output_file = open("data.txt", 'w')

    input_file = open(filename, "r")
    for line in input_file:
        line = line.strip()
                if not line.startswith("(") or line.startswith(""):
                        output_file.write(line)        
    output_file.close()
if __name__ == "__main__":
process_file(sys.argv[1])

Answer 1

In addition to line.startswith("") always being true, line.strip() will remove the leading tab forcing the tabbed data to be written as well. change it to line.rstrip() and use \t to test for a tab. That part of your code should look like:

line = line.rstrip()
if not line.startswith(('(', '\t')):
    #....

In response to your question in the comments:

#edited in response to comments in post
for i, line in input_file:
    if i % 4 == 0:
        output_file.write(line)