python printing a blank line on the first line when writing to a file

Question

I'm stuck on why my code is printing a blank line before writing text to a file. What I am doing is reading two files from a zipped folder and writing the text to a new text file. I am getting the expected results in the file, except for the fact that there is a blank line on the first line of the file.

def test():
    if zipfile.is_zipfile(r'C:\Users\test\Desktop\Zip_file.zip'):
        zf = zipfile.ZipFile(r'C:\Users\test\Desktop\Zip_file.zip')
        for filename in zf.namelist():
            with zf.open(filename, 'r') as f:
                words = io.TextIOWrapper(f)
                new_file = io.open(r'C:\Users\test\Desktop\new_file.txt', 'a')
                for line in words:
                    new_file.write(line)
                new_file.write('\n')
    else:
        pass

    zf.close()
    words.close()
    f.close()
    new_file.close()

Output in new_file (there is a blank line before the first "This is a test line...")

This is a test line...
This is a test line...
this is test #2
this is test #2

Any ideas?

Thanks!

Solution

My guess is that the first file in zf.namelist() doesn't contain anything, so you skip the for line in words loop for that file and just do new_file.write('\n'). It's difficult to tell without seeing the files that you're looping over; perhaps add some debug statements that print out the files' names and some info, e.g. their size.