Python Read/Write Text Files

Question

I have a .rtf file containing a unique string on each line, 1000 lines or so. I want to remove the last character off of each of those lines, and output the result into a new .csv file so that I can add it later on into a database.

I tried to do it in python, by opening both files and looping through each line, however the output file would remain empty and I got 0 errors throughout the whole thing. How can I implement another solution in python? Thanks in advance!

input_file = "usernames.rtf"
output_file = "outputfile.csv"

character_to_remove = "."

with open(input_file, "r") as input_f, open(output_file, "w") as output_f:
    for line in input_f:
        if line[-1] == character_to_remove:  
          modified_line = line.rstrip(line[-1])
          output_f.write(modified_line + "\n")
        else:
          output_f.write(line + "\n")

input_f.close()
output_f.close()

print("Character removal completed. Check the output file:", output_file)

Answer 1

Each line ends with '\n'. So there are two mistakes:

1. You need to replace character_to_remove = "." with character_to_remove = ".\n"
2. Then you need to replace line.rstrip(line[-1]) with line.rstrip(line[-(len(character_to_remove)])

This would just be a fix for YOUR code. As mentioned, you should use .readlines() to avoid such problems. Also, use line.endswith(<string>) for your if statement. This function returns True if the string line ends with the given string. There is also the equivalent for checking the begin of a string called line.startswith(<string>).

Edit: This should fit for your problem. As mentioned in some comments, you have to use the right format for a csv file. The csv module, which is part of the standard Python installation, should be enough. Pandas also provides a good csv writing function.

import csv  # to create a csv file

input_file = "usernames.rtf"
output_file_txt = "outputfile.txt"
output_file_csv = "outputfile.csv"

character_to_remove = "."

# if you want to remove multiple characters
char_len = len(character_to_remove)

with open(input_file, "r") as input_f, open(output_file_txt, "w") as output_f_txt, open(output_file_csv, "w") as output_f_csv:
    csvwriter = csv.writer(output_f_csv)
    for line in input_f.readlines():
        line = line.strip()  # remove trailing spaces and linebreaks

        if line.endswith(character_to_remove):
          line = line.rstrip(line[-char_len])

        output_f_txt.write(line + "\n")
        csvwriter.writerow(line)  # for further options read csv manual

print("Character removal completed. Check the output file:", output_file_txt, output_file_csv)