CODEWITHSUNDEEP
pythonloopsiteratoriteration
harekuin
harekuin

Reputation: 45

Can't get the next line using next() in a loop (python)

I'm trying to write a code that iterates through a txt file and only gets the lines I want to print them out.

the text file should look like so:

mimi
passwordmimi
mimi johnson
somejob
joji
passwordjoji
jojo
somejob
john
passwordjohn
jonathan
somejob
....

and so on. this text file contains basically a user information (for a log in). I need to make everyone's username print out and their real name (ex: mimi and mimi johnson.) and only those. I don't want the current user's info to print out (in this ex: joji)

here is my code:

username="joji"

file=open("username.txt","r") 
x=file.readlines()

x=[item.rstrip('\n') for item in x]

x=iter(x)

for line in x:
      if line==username:
              next(x,None)
              next(x,None)
              next(x,None)
      else:
              print line + " username"    ****username should print out. ex:mimi or john
              next(x,None)
              print line +" real name   ****real name should print out. ex: mimi johnson or jonathan

for whatever reason when I run this program and i print out the second **** i put, it prints out the username's twice. (so ex:

mimi username
mimi real name
mimi johnson username
mimi johnson real name
john username
john real name
jonathan username
jonathan real name
....

why is that? it should print out 

mimi username
mimi johnson real name
john username
jonathan realname 
...

if someone could help me out i'd be really grateful i dont get python. Im also open to any other suggestions to do this.

EDIT::: i tried making a change with a suggestion this is the outcome:

new block of code:

else: 
      print line + "username" 
      line =next(x,None)
      print line

this is the new outcome:

 mimi username
 passmimi real name
 mimi johnson username
 somejob real name
 john username
 passjohn real name
 jonathan username
 somejob real name(***im assuming this one is from john's job)

:/ its not doing what its supposed to

Upvotes: 0

Views: 1036

Answers (1)

odrling
odrling

Reputation: 134

I would recommend using regex to parse this file:

import re

# regex expression to parse the file as you provided it
# you could access the parseddata as a dict using the 
# keys "username", "password", "real_name" and "job"
ex = "\n*(?P<username>.+)\n(?P<password>.+)\n(?P<real_name>.+)\n(?P<job>.+)[\n\$]"

with open("usernames.txt", 'r') as users:
    matches = re.finditer(ex, users.read())
    for match in matches:
        user = match.groupdict()  # user is a dict

        # print username and real name
        print(user['username'], "username", user['real_name'], "real name")

Edit: I figured that regex was not really needed here as the format of this file is quite simple. So here is the same thing without using regex.

def parse(usersfile):
    # strip line break characters
    lines = (line.rstrip('\n') for line in usersfile)

    # keys to be used in the dictionnary
    keys = ('username', 'password', 'real_name', 'job')

    while True:
        # build the user dictionnary with the keys above
        user = {key: line for key, line in zip(keys, lines)}

        # yield user if all the keys are in the dict
        if len(user) == len(keys):
            yield user
        else:  # stop the loop
            break

with open("usernames.txt", 'r') as usersfile:
    for user in parse(usersfile):
        # print username and real name
        print(user['username'], "username", user['real_name'], "real name")

Upvotes: 1

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