CODEWITHSUNDEEP
pythonfunctionpickle
python_enthusiast
python_enthusiast

Reputation: 946

Function for pickle

I am trying to build a function to store data in a pickle file. I know that using pickle this way works:

with open('x.pickle', 'wb') as f:
    pickle.dump(x, f)

But I actually want to make a function out of it so I don't have to write it again and again. Here is what I have tried:

def pickle_dump(x):
    with open('%s.pickle'%x, 'wb') as f:
        pickle.dump(x, f)
    return

When we use 'with', and the file does not exist, it creates a file. I supposed that it would also work when inside a function, but instead it returned me a File Not Found Error.

Any help is appreciated.

Upvotes: 2

Views: 1520

Answers (2)

Brad Solomon
Brad Solomon

Reputation: 40878

It looks like you're confusing the string path name with your actual object. They are two different things.

def pickle_dump(path, x):
   """Pickle object `x` to `path`."""
    with open('%s.pickle' % path, 'wb') as f:
        pickle.dump(x, f)

Example:

import pandas as pd
df = DataFrame() # the actual object you want to pickle
pickle_dump(path='files/filename', x=df)

To do the same thing in reverse:

def pickle_load(path): 
    with open('%s.pickle' %path, 'rb') as f: 
        return pickle.load(f)

Now to run this you would assign a variable to the returned value from the function:

result = pickle_load('mypath/filename')

In your comment, you named a variable x in the function body. But realize that is a local variable. You can't access it from outside of the function. That's a case where you want the return statement.

Upvotes: 1

Alexander
Alexander

Reputation: 109546

Pass both the object and filename.

import cPickle as pickle  # Python 2

def pickle_dump(obj, filename):
    if filename.split('.')[-1] != 'p':
        filename += '.p'  # Add pickle file extension `.p` if needed.
    with open(filename, 'wb') as f:
        pickle.dump(obj, f, protocol=pickle.HIGHEST_PROTOCOL)

Upvotes: 1

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