How can i parse a txt file into lists in Python

Question

I am not far from a new bee in Python and i would like to parse a file as is :

Paris, 458 boulevard Saint-Germain
Paris, 343 boulevard Saint-Germain
Marseille, 343 boulevard Camille Flammarion
Marseille, 29 rue Camille Desmoulins
Marseille, 1 chemin des Aubagnens

The file contains : City, Street number, Street Type and Street Name

This order is always the same and the City is followed by a comma.

I had done this for now:

#!/usr/bin/python3.4                                                                          

import readline
import sys

try:
    f = open(sys.argv[1])
except:
    sys.exit()

lines = f.readlines()
print(lines)

And i get this output:

['Paris, 458 boulevard Saint-Germain\n', 'Paris, 343 boulevard Saint-Germain\n', 'Marseille, 343 boulevard Camille Flammarion\n', 'Marseille, 29 rue Camille Desmoulins\n', 'Marseille, 1 chemin des Aubagnens\n']

Seems to be the thing to do but now i have 2 questions:

How can I make some lists for each one of the type (City, number, streetType, streetName) ?
Is there a librairy in Python that parses adresses in a list ? One that you would recommend ?

1st question:- How can I make some lists for each one of the type:::-- It's already a list of addresses. What else do u want? — Deca
– Deca, Commented Jul 1, 2016 at 11:03
I am quite new to it but i have basic knowledge in programming so i think i could check this out and understand it .. i hope — Thomas Beaudet
– Thomas Beaudet, Commented Jul 1, 2016 at 11:04
Ok maybe i forgot to tell you guys the goal of the project is to make a basic autocomplete from words that we get from that famous .txt file. — Thomas Beaudet
– Thomas Beaudet, Commented Jul 1, 2016 at 11:06
Think through your design first. Do you really want a list of house numbers? For example, a dictionary of street names as keys each with a list of house numbers might be useful. — cdarke
– cdarke, Commented Jul 1, 2016 at 11:06

PM 2Ring · Accepted Answer · 2016-07-01 11:55:55Z

2

There are various data structures that you could store this data in. You could store the data from each line in a tuple containing (city_name, street_number, street_type, street_name), and then store each of those tuples into a list. A slightly nicer option is to store the data into a list of dictionaries. Here's a short demo.

fname = 'citydata.txt'

addresses = []
keys = ('city', 'num', 'type', 'name')

with open(fname) as f:
    for line in f:
        line = line.rstrip()
        city, line = line.split(',', 1)
        num, street_type, street_name = line.split(None, 2)
        t = (city, num, street_type, street_name)
        print(t)
        addresses.append(dict(zip(keys, t)))

print()
for row in addresses:
    print(row)

print()
for row in addresses:
    print(row['num'])

output

('Paris', '458', 'boulevard', 'Saint-Germain')
('Paris', '343', 'boulevard', 'Saint-Germain')
('Marseille', '343', 'boulevard', 'Camille Flammarion')
('Marseille', '29', 'rue', 'Camille Desmoulins')
('Marseille', '1', 'chemin', 'des Aubagnens')

{'city': 'Paris', 'num': '458', 'type': 'boulevard', 'name': 'Saint-Germain'}
{'city': 'Paris', 'num': '343', 'type': 'boulevard', 'name': 'Saint-Germain'}
{'city': 'Marseille', 'num': '343', 'type': 'boulevard', 'name': 'Camille Flammarion'}
{'city': 'Marseille', 'num': '29', 'type': 'rue', 'name': 'Camille Desmoulins'}
{'city': 'Marseille', 'num': '1', 'type': 'chemin', 'name': 'des Aubagnens'}

458
343
343
29
1

answered Jul 1, 2016 at 11:55

PM 2Ring

55.6k6 gold badges96 silver badges201 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

Thomas Beaudet Over a year ago

What an answer ! Thanks it really helps my understanding of this language.

Thomas Beaudet Over a year ago

Last question is : I am currently learning C and C++ and i was wondering if there was a same kind of "error handling" as in C or C++. By that I mean checking returns of open() or other functions ? Thanks a lot for help !

cdarke Over a year ago

Use Exception handling in Python - see docs.python.org/3/tutorial/errors.html

PM 2Ring Over a year ago

@ThomasBeaudet: I'm glad you like my answer. Don't forget to upvote it, once you have enough points. :) Yes, Python has exception handling. See docs.python.org/3/tutorial/errors.html

PM 2Ring Over a year ago

Python works at a higher level than C/C++. For example, I have used with to open the file. This automatically closes the file if there is some error inside the with block. In C you'd need to do a lot more explicit error checking.

I159 · Accepted Answer · 2016-07-01 12:13:29Z

2

(EDIT)

Actually you don't need any extra libs. It is simple operation which could be done with list comprehension or generator or map function and split , strip str object methods if you could split by the single character

with open(sys.argv[1]) as f:
    lines = f.readlines() 
    split = lambda x: x.replace(',', '').split()
    addresses_lists = map(split, lines)

If you have more complex condition to split - use re module to parse a pattern you need. Definitely you need split function from re module.

edited Jul 1, 2016 at 12:13

answered Jul 1, 2016 at 11:43

I159

31.4k32 gold badges102 silver badges138 bronze badges

4 Comments

PM 2Ring Over a year ago

Note that this does not strip the comma off the city name.

I159 Over a year ago

@PM2Ring, yep it could be processed after or with more complex lambda used with map for example.

Thomas Beaudet Over a year ago

No need, both answers helped me a lot since i'm really new to Python ! i'll just gather every possible infos i can ! Again, thanks a lot guys !

I159 Over a year ago

@PM2Ring, but you had a good point and more obvious syntax. That is good for studying ;)

Collectives™ on Stack Overflow

How can i parse a txt file into lists in Python

2 Answers 2

5 Comments

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related