How to get a dictionary from a json file in Python?

Question

I got this code for implementing my needing:

import json

json_data = []
with open("trendingtopics.json") as json_file:
    json_data = json.load(json_file)

for category in json_data:
    print category
    for trendingtopic in category:
        print trendingtopic

And this is my json file:

{
    "General": ["EPN","Peña Nieto", "México","PresidenciaMX"],
    "Acciones politicas": ["Reforma Fiscal", "Reforma Energética"]
}

However I'm getting this printed:

Acciones politicas
A
c
c
i
o
n
e
s

p
o
l
i
t
i
c
a
s
General
G
e
n
e
r
a
l

I want to get a dictionary being Strings the keys and got a list as value. Then iterate over it. How can I accomplish it?

Did you mean for trendingtopic in json_data[category]: in your inner loop? — waffle paradox
– waffle paradox, Commented Feb 6, 2014 at 0:33

Bugs · Accepted Answer · 2014-02-06 00:34:45Z

4

json_data is a dictionary. In your first loop, you're iterating over a list of the dictionary's keys:

for category in json_data:

category will contain key strings - General and Acciones politicas.

You need to replace this loop, which iterates over keys' letters:

for trendingtopic in category:

with the below, so that it iterates over the dictionary elements:

for trendingtopic in json_data[category]:

answered Feb 6, 2014 at 0:34

Bugs

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1 Comment

hughdbrown Over a year ago

ALternatively, you could iterate like this: for key, value in json_data.iteritems(): print key; for item in value: print item

Nick T · Accepted Answer · 2014-02-06 00:52:32Z

3

I'd use the .iteritems() method of the dictionary which returns key/value pairs:

for category, trending in json_data.iteritems():
    print category
    for topic in trending:
        print topic

edited Feb 6, 2014 at 0:52

answered Feb 6, 2014 at 0:44

Nick T

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4 Comments

diegoaguilar Over a year ago

Does iteritems implies any higher or lower cost to the operation against simple loop?

Nick T Over a year ago

I think for ... in mydict: (the 'simple loop') is equivalent to for ... in mydict.iterkeys():. When you use iteritems() I'd guess it's a tiny bit faster because it pulls the key/value pair as a unit, rather than having to go back and lookup whatever value. My motivation is just that it makes the code look a little better.

diegoaguilar Over a year ago

Great, what happens if my json gets not same structure, for example, somtimes values are lists, sometimes other dictionaries, etc

Nick T Over a year ago

If trending above was a dictionary rather than a list, it would just print it's keys. If that's what you want, great, but if you need to handle them differently, then you need different code for each.

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