Save a dictionary to a file (alternative to pickle) in Python?

wKavey picture wKavey · Feb 4, 2011 · Viewed 89.7k times · Source

Answered I ended up going with pickle at the end anyway

Ok so with some advice on another question I asked I was told to use pickle to save a dictionary to a file.

The dictionary that I was trying to save to the file was

members = {'Starspy' : 'SHSN4N', 'Test' : 'Test1'}

When pickle saved it to the file... this was the format

(dp0
S'Test'
p1
S'Test1'
p2
sS'Test2'
p3
S'Test2'
p4
sS'Starspy'
p5
S'SHSN4N'
p6
s.

Can you please give me an alternative way to save the string to the file?

This is the format that I would like it to save in

members = {'Starspy' : 'SHSN4N', 'Test' : 'Test1'}

Complete Code:

import sys
import shutil
import os
import pickle

tmp = os.path.isfile("members-tmp.pkl")
if tmp == True:
    os.remove("members-tmp.pkl")
shutil.copyfile("members.pkl", "members-tmp.pkl")

pkl_file = open('members-tmp.pkl', 'rb')
members = pickle.load(pkl_file)
pkl_file.close()

def show_menu():
    os.system("clear")
    print "\n","*" * 12, "MENU", "*" * 12
    print "1. List members"
    print "2. Add member"
    print "3. Delete member"
    print "99. Save"
    print "0. Abort"
    print "*" * 28, "\n"
    return input("Please make a selection: ")

def show_members(members):
    os.system("clear")
    print "\nNames", "     ", "Code"
    for keys in members.keys():
        print keys, " - ", members[keys]

def add_member(members):
    os.system("clear")
    name = raw_input("Please enter name: ")
    code = raw_input("Please enter code: ")
    members[name] = code
    output = open('members-tmp.pkl', 'wb')
    pickle.dump(members, output)
    output.close()
    return members


#with open("foo.txt", "a") as f:
#     f.write("new line\n")

running = 1

while running:
    selection = show_menu()
    if selection == 1:
        show_members(members)
        print "\n> " ,raw_input("Press enter to continue")
    elif selection == 2:
        members == add_member(members)
        print members
        print "\n> " ,raw_input("Press enter to continue")
    elif selection == 99:
        os.system("clear")
        shutil.copyfile("members-tmp.pkl", "members.pkl")
        print "Save Completed"
        print "\n> " ,raw_input("Press enter to continue")

    elif selection == 0:
        os.remove("members-tmp.pkl")
        sys.exit("Program Aborted")
    else:
        os.system("clear")
        print "That is not a valid option!"
        print "\n> " ,raw_input("Press enter to continue")

Answer

David Wolever picture David Wolever · Feb 4, 2011

Sure, save it as CSV:

import csv
w = csv.writer(open("output.csv", "w"))
for key, val in dict.items():
    w.writerow([key, val])

Then reading it would be:

import csv
dict = {}
for key, val in csv.reader(open("input.csv")):
    dict[key] = val

Another alternative would be json (json for version 2.6+, or install simplejson for 2.5 and below):

>>> import json
>>> dict = {"hello": "world"}
>>> json.dumps(dict)
'{"hello": "world"}'