Parsing a simple text file using Python

Question

I'm an moderator of a forum and I need to prune all the bots that register on there.
As you can see below, I can list all the users by:

Username number_of_mssages register_date

Example:

- Thurman Valsin0190 0 Sat Jan 14, 2012 5:00 pm
- Rubye Tones01AD 0 Sat Jan 14, 2012 4:59 pm

I need a super simple Python little program that parses me each line of a text file, so I can get, from the string above, only the nick names.

- Thurman Valsin0190
- Rubye Tones01AD

This means that the program has to delete for each line the 0 and everything that is behind him. The text is taken from a .txt file.
I know this is not that difficult but I'm not a lot into Python. Thanks in advance!

• Vaughn Cato: What you are calling a username appears to be two separate things -- a nickname and a username.
• user963658: "Thurman Valsin0190" is the username.
• Rik Poggi: That 0 will always be 0? or can be any one digit number?

Answer 1

It's not a python question really, it's a regex/string parsing question...

Is it correct to say that every line contains the nickname, a tab character, and then a 0?

Then it should be as simple as:

(assuming line contains a single line from the file)

nickname = line.split("\t")[0]

Answer 2

consider using regular expressions:

import re
pattern = re.compile(r'(.*?)\s+0\s+')
pattern.findall('- Thurman Valsin0190 0 Sat Jan 14, 2012 5:00 pm')[0] 
# - Thurman Valsin0190

• user963658: I need a generic program, not only for a single username.
• qiao: @user963658 This is generic, the pattern is match the substring before multiple white spaces following a 0 with trailing multiple whitespaces. You may give it a try.

Answer 3

Why not split on 0 with leading spaces (or tabs) included as part of split key to avoid splitting other zeros:

with open("filename.txt", "r") as f:
 for line in f:
 nick = line.split(" 0 ")[0].strip() # OR .split("\t0\t") if those are tabs
 print nick

• user963658: And if I need to save the results on the same file, deleting the un-parsed lines? (I need only a text file with the pared lines, the ones only with the username)
• sharjeel: Run this program with shell and redirect its output to another .txt file. Delete the original .txt file and rename the new file to original file. e.g. python script.py > out.txt rm filename.txt mv out.txt filename.txt

Answer 4

Parse by splitting on " 0 " string e.g., extract-nickname.py:

#!/usr/bin/env python
import fileinput
for line in fileinput.input():
 nick, sep, rest = line.partition(" 0 ")
 if sep:
 print(nick.strip())

It assumes that nicknames can't contain " 0 " and leading/trailing whitespace is not a part of a nickname. Otherwise you could use line.partition("\t") if a tab character is a separator between Username and number_of_mssages.

Example

$ python extract-nickname.py log.txt
- Thurman Valsin0190
- Rubye Tones01AD

If you need to change the file inplace then you could specify inplace=True parameter to fileinput.input() function.