Accessing text file

Dev Shed Forums Sponsor:

February 24th, 2004, 06:47 AM

flixxer

Contributing User

Join Date: Feb 2004

Posts: 44

Time spent in forums: < 1 sec
Reputation Power: 10

Accessing text file

If i have a text file with these value:

Code:

## -- Text file --##

nickname:realname
something:anythin

##--- Text file --##

how can I display the value of eg. nickname based on user input(eg: if the user type in nickname the the screen will display the real name)

February 24th, 2004, 07:51 AM

sfb

Contributing User

Join Date: Nov 2003

Posts: 623

Time spent in forums: 3 Days 5 h 53 m 21 sec
Reputation Power: 33

Read the lines of the file, and store them somewhere. Then just lookup in the store when someone types something.
If you only want one-way lookups then a Dictionary is good to use.

Code:

pairs = {}

for line in file('pairs.txt'):
    try:
        x, y = line.split(':')
        pairs[x] = y
    except: 
        #Ignore empty lines, etc.
        pass

try:
    val = raw_input('Type something: ')
    print val, "links to", pairs[val]
except KeyError:
    print val, "not found in pairs list"

February 24th, 2004, 09:54 AM

Grim Archon

Mini me.

Join Date: Nov 2003

Location: Cambridge, UK

Posts: 783

Folding Points: 1488 Folding Title: Novice Folder

Time spent in forums: 3 Days 2 h 15 m 57 sec
Reputation Power: 12

Often these files are edited by hand and around the values you want you get unwanted character codes (e.g. tabs and spaces) . You can tidy it up easily:

pairs[x.strip()] = y.strip()

That might save a few hours bug-hunting

.
Grim

__________________
*** Experimental Python Markup CGI V2 ***

February 24th, 2004, 03:02 PM

netytan

Hello World :)

Join Date: Mar 2003

Location: Hull, UK

Posts: 2,537

Time spent in forums: 1 Week 2 Days 18 h 17 m 47 sec
Reputation Power: 68

Just another example, based on sfb's with a few minor differences. Mainly to show the "if 'key' in dict" statment and stop unpacking errors.

1. only splitting on the first colon, this helps stop unpacking errors resulting from lines containing more than one colon.
2. uses if statments instead of try-except blocks. Just a personal preferance

Code:

#!/usr/bin/env python

parts = {}

for line in file('file.txt'):
    try:
        x, y = line.split(':', 1)
        parts[x] = y
    except:
        pass
     
value = raw_input('Enter a value')

if value in parts:
    print value, 'links to', parts[value]
else:
    print value, 'not found in parts'

Note: this does requite Python 2.3.

Mark.

__________________
programming language development: www.netytan.com – Hula

Last edited by netytan : February 24th, 2004 at 03:14 PM.

Accessing text file

Developer Shed Advertisers and Affiliates