Question

I’m having some trouble sorting data from a text file by a certain field. Possibly by multiple fields later. The .txt is several thousands of lines of code. I’m brand new to python so my code is probably a bit messy. For example, this is the textfile i would read from:

stuff
123 1200 id-aaaa [e-mail]
322 1812 id-wwww [e-mail]
839 1750 id-wwww [e-mail]
500 0545 id-aaaa [e-mail]
525 1322 id-bbbb [e-mail]

my code so far is as follows:

filelist = open("info.txt").readlines()
splitlist = list()

class data:
    def __init__(self, eventName, time, identity, domain):
        self.evenName = eventName
        self.time = time
        self.identity = identity
        self.domain = domain

for line in filelist:
    filelist = list.split(', ')
    splitlist.append(filelist)

for column in splitlist:
    if (len(column) > 1): #to skip the first line
        eventName = column[0].strip()
        time = column[1].strip()
        identity = column[2].strip()
        domain = column[3].strip()

I want to sort the .txt file line by line by the identity, then maybe by time. I saw that this could be done by classes in the python tutorial, so i’m trying to go that route. Please advise. Thank you!

Answer 1

with open("info.txt") as inf:
    data = []
    for line in inf:
        line = line.split()
        if len(line)==4:
            data.append(line)

data.sort(key=lambda s:(s[2],s[1]))

If you want to get a bit fancier,

from collections import namedtuple
Input = namedtuple('Input', ('name', 'time', 'identity', 'domain'))

with open("info.txt") as inf:
    inf.next()  # skip header
    data = [Input(*(line.split()) for line in inf]

data.sort(key=lambda s:(s['identity'],s['time']))

If you really, really want to use a class, try:

import time

class Data(object):
    def __init__(self, event, time_, identity, domain):
        self.event = event
        self.time = time.strptime(time_, "%H%M")
        self.identity = identity
        self.domain = domain

with open("info.txt") as inf:
    data = []
    for line in inf:
        try:
            data.append(Data(*(line.split()))
        except TypeError:
            # wrong number of arguments (ie header or footer)
            pass

data.sort(key=lambda s:(s.identity,s.time))