CODEWITHSUNDEEP
pythonfile-io
user3014014
user3014014

Reputation: 819

Python Homework - file i/o - read file and turn into dictionary

I need to create a function that takes no arguments and reads back the dictionary that is in a previously-saved file. I must first determine if the file exists. If it does, I must read the contents of the file and return it as a dictionary. If not, return [].

I'm fairly new to Python and I've been brain dead looking at this for a couple hours now. Any help would be much appreciated!

For example: 

dave 12
brad 18
stacy 8

This would now be read as {'dave': 12, 'brad': 18, 'stacy': 8}.

So far I have this:

def readit():

    file1 = open('save.txt', 'r')
    data = []
    lines = file1.readlines()
    for i in range(len(lines)):
        data.append(lines[i].split('\n'))
    return data
    file1.close()

Upvotes: 0

Views: 1518

Answers (2)

Martijn Pieters
Martijn Pieters

Reputation: 1125058

This'll do it:

import os.path

def readit():
    filename = 'save.txt'
    if not os.path.isfile(filename):
        return {}
    with open(filename) as ifh:
        return dict(line.split() for line in ifh)

This first tests if the file exists; if it does not an empty dictionary is returned.

If there are spaces between the names, use .rsplit(None, 1); this'll split on the last whitespace within the line only:

def readit():
    filename = 'save.txt'
    if not os.path.isfile(filename):
        return {}
    with open('save.txt') as ifh:
        return dict(line.rsplit(None, 1) for line in ifh)

which will turn:

Martijn Pieters 42
user3014014 38

into

{'Martijn Pieters': '42', 'user3014014': '38'}

Note the with statement here also. This uses the file object as a context manager, meaning that as soon as the block exits (using return, due to an exception or simply because the block ends) then the file is automatically closed for you. Your file1.close() line on the other hand will never be executed as it is placed after the return statement.

The above, of course, gives us strings for values. Lets expand this to produce integer values instead:

def readit():
    filename = 'save.txt'
    if not os.path.isfile(filename):
        return {}
    with open('save.txt') as ifh:
        return {key: int(value) for line in ifh for key, value in (line.rsplit(None, 1),)}

This produces:

{'Martijn Pieters': 42, 'user3014014': 38}

for my sample input.

Upvotes: 4

sushant-hiray
sushant-hiray

Reputation: 1898

def readit():
  data = dict(x.split for x in open("save.txt"))
  return data

This should help you get it!

Upvotes: 1

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