Getting values from JSON file

Question

I am trying to get the values from count and add them to find the total sum. The code I have written is:

import json
data= '''
{
  "note":" sample data ",
  "comments":
  [
    {
      "School":"UCLA",
      "count":97
    },
    {
      "School":"MIT",
      "count":97
    },
    {
      "School":"Rutgers",
      "count":90
    }
  ]
}'''

number=list()
a=0
b=0
info = json.loads (data)
print json.dumps(info, indent=4)
for i in info:
    number= i["comments"][0]["count"]
for n in number:
    a=float(n)
    b+=a
print b

When I execute this, the output I am getting is:

Traceback (most recent call last):
  File "testty.py", line 28, in <module>
    number= i["comments"][0]["count"]
TypeError: string indices must be integers

Can some one please tell me what I am doing wrong and how to fix it.

Thanks

Thank you all, its working now. But if I want to get the values using the step: number= i["comments"][0]["count"] , What change should I make for it to work ? — sooraj
– sooraj, Commented May 27, 2016 at 0:48
Hi Merlin, I am trying to capture the value of count using the command: number= i["comments"][0]["count"]. But I am getting the error : Traceback (most recent call last): File "testty.py", line 28, in <module> number= i["comments"][0]["count"] TypeError: string indices must be integers Even though my code is working now by using what @Barmar mentioned, I am wondering what changes should I make to the above command so that i can use it in my code. — sooraj
– sooraj, Commented May 27, 2016 at 1:14
I am just trying to understand how the command number= i["comments"][0]["count"] , works and why it's not working in this case. Thank you for your time. — sooraj
– sooraj, Commented May 27, 2016 at 1:16

John La Rooy · Accepted Answer · 2016-05-27 00:43:28Z

3

You should be looping over info["comments"] which is a list. You can also use the sum function to total the values

b = sum(float(i["count"]) for i in info["comments"])

answered May 27, 2016 at 0:43

John La Rooy

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Comments

Merlin · Accepted Answer · 2016-05-27 01:40:08Z

2

This is python list comprehension:

tt = sum([float(row['count']) for row in info['comments']])
print tt

or this is "for" loops

tt = [] 
for row in info['comments']:
    tt.append(float(row['count']))

b = sum(tt)
print b

List comprehension is usually faster...

Your code:

    data= '''
[{
  "note":" sample data ",
  "comments":
  [
    {
      "School":"UCLA",
      "count":97
    },
    {
      "School":"MIT",
      "count":97
    },
    {
      "School":"Rutgers",
      "count":90
    }
  ]
}]'''

Use the above as data and your code should work... You are missing opening '[' and closing ']'...

edited May 27, 2016 at 1:40

answered May 27, 2016 at 1:04

Merlin

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Comments

Ignacio Vazquez-Abrams · Accepted Answer · 2016-05-27 00:40:57Z

2

This:

for i in info:

iterates over the dict, which yields keys, which are strings. Access info directly instead.

answered May 27, 2016 at 0:40

Ignacio Vazquez-Abrams

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Comments

Barmar · Accepted Answer · 2016-05-27 00:41:58Z

1

The top-level JSON object is not an array, so you shouldn't iterate over it. The array is in info["comments"], so do

for i in info["comments"]:
    a = float(i["count"])
    b += a
print b

answered May 27, 2016 at 0:41

Barmar

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