CODEWITHSUNDEEP
pythondictionary
sarandonga2912
sarandonga2912

Reputation: 97

create a dictionary with a .txt file in python

I have a list of pairs like pair_users = [('a','b'), ('a','c'), ('e','d'), ('e','f')] when I saved this I used this code:

with open('pair_users.txt', 'w') as f:
  f.write(','.join('%s' % (x,) for x in pair_users))

Then, when I want to use it in another notebook to create a dictionary which will look like this {'a': ['b', 'c'], 'b': [], 'c': [], 'd': [], 'e': ['d', 'f'], 'f': []}

to create that dictionary I am using this code:

graph = {}
for k, v in pair_users:
    graph.setdefault(v, [])
    graph.setdefault(k, []).append(v)

graph

but my problem is when I run the graph code after opening the file I saved pair_users = open('/content/pair_users.txt', 'r') the result I get is an empty dictionary {}.

This is the output I have when I open the file

enter image description here

When I use the code to create the graph without saving the list as txt file I get the right answer, my problem is when I save it and then I open it.

Here it worked for example:

enter image description here

Thanks in advance for your ideas!

Upvotes: 0

Views: 102

Answers (3)

SomeDude
SomeDude

Reputation: 14228

The result you get when you read the file is just a single string. You cannot iterate the string as k,v. You could either parse the string into tuples by your own parsing or you could go with an option like pickle.

With pickle it is :

import pickle
with open('pair_users.pkl', 'wb') as f:
    pickle.dump(pair_users, f)
    f.close()

with open('pair_users.pkl', 'rb') as f:
    pair_tuple = pickle.load(f)
    f.close()
    print(pair_tuple)

Upvotes: 1

Trenton McKinney
Trenton McKinney

Reputation: 62373

  • The issue is, pair_users is a str type when it's read back in.
  • Use ast.literal_eval to convert the string to a tuple.
from ast import literal_eval

pair_users = open('test.txt', 'r')

pair_users= literal_eval(pair_users.read())

graph = {}
for k, v in pair_users:
    graph.setdefault(v, [])
    graph.setdefault(k, []).append(v)

graph
[out]: 
{'b': [], 'a': ['b', 'c'], 'c': [], 'd': [], 'e': ['d', 'f'], 'f': []}

Upvotes: 1

Jan Stránský
Jan Stránský

Reputation: 1691

Apart from using pickle or parsing the string as proposed in the other answeres, you can use some "more universal format", e.g. JSON:

import json

pair_users = [('a','b'), ('a','c'), ('e','d'), ('e','f')]
with open('pair_users.txt', 'w') as f:
    json.dump(pair_users,f)

with open("pair_users.txt") as f:
    pair_users = json.load(f)

graph = {}
for k, v in pair_users:
    graph.setdefault(v, [])
    graph.setdefault(k, []).append(v)
print(graph)

Upvotes: 1

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