How to save a dictionary to a file?

Question

I have problem with changing a dict value and saving the dict to a text file (the format must be same), I only want to change the member_phone field.

My text file is the following format:

memberID:member_name:member_email:member_phone

and I split the text file with:

mdict={}
for line in file:
    x=line.split(':')
    a=x[0]
    b=x[1]
    c=x[2]
    d=x[3]
    e=b+':'+c+':'+d

    mdict[a]=e

When I try change the member_phone stored in d, the value has changed not flow by the key,

def change(mdict,b,c,d,e):
    a=input('ID')
    if a in mdict:
        d= str(input('phone'))
        mdict[a]=b+':'+c+':'+d
    else:
        print('not')

and how to save the dict to a text file with same format?

Answer 1

Python has the pickle module just for this kind of thing.

These functions are all that you need for saving and loading almost any object:

def save_obj(obj, name ):
    with open('obj/'+ name + '.pkl', 'wb') as f:
        pickle.dump(obj, f, pickle.HIGHEST_PROTOCOL)

def load_obj(name ):
    with open('obj/' + name + '.pkl', 'rb') as f:
        return pickle.load(f)

These functions assume that you have an obj folder in your current working directory, which will be used to store the objects.

Note that pickle.HIGHEST_PROTOCOL is a binary format, which could not be always convenient, but is good for performance. Protocol 0 is a text format.

In order to save collections of Python there is the shelve module.