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!

What you are calling a username appears to be two separate things -- a nickname and a username. — Vaughn Cato
– Vaughn Cato, Commented Jan 14, 2012 at 16:41
That 0 will always be 0? or can be any one digit number? — Rik Poggi
– Rik Poggi, Commented Jan 14, 2012 at 17:20

Zando · Accepted Answer · 2012-01-14 16:42:17Z

3

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]

answered Jan 14, 2012 at 16:42

Zando

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Comments

qiao · Accepted Answer · 2012-01-14 16:43:03Z

3

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

answered Jan 14, 2012 at 16:43

qiao

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2 Comments

user963658 Over a year ago

I need a generic program, not only for a single username.

qiao Over a year ago

@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.

sharjeel · Accepted Answer · 2012-01-14 16:57:38Z

1

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

answered Jan 14, 2012 at 16:57

sharjeel

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2 Comments

user963658 Over a year ago

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 Over a year ago

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

jfs · Accepted Answer · 2012-01-14 17:17:15Z

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.

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