for loop Optimization

Question

I have a sample Json as mentioned below

[{
    "Name": "Kim",
    "Details": {
        "Age": 43,
        "Gender": "Male",
        "Education": [{
                "Primary": "Xavier",
                "Percentage": 90,
                "subject": [{
                        "sub": "Math",
                        "Perf": "Good"
                    },
                    {
                        "sub": "Sci",
                        "Perf": "Averge"
                    }, {
                        "sub": "Eco",
                        "Perf": "Good"
                    }
                ],
                "Marks": [{
                        "Mark": 90,
                        "Grade": "A"

                    },
                    {
                        "Mark": 92,
                        "Grade": "S"
                    }, {
                        "Mark": 80,
                        "Grade": "B"
                    }
                ]
            },
            {
                "Seconday": "Anthony",
                "Percentage": 98,
                "subject": [{
                    "sub": "Math",
                    "Perf": "Good"
                }],
                "Marks": [{
                    "Mark": 100,
                    "Grade": "S"
                }]
            },
            {
                "Bachelor": "Boston",
                "Percentage": 90,
                "subject": [{
                    "sub": "Computers",
                    "Perf": "Good"
                }],
                "Marks": [{
                    "Mark": 90,
                    "Grade": "A"
                }]
            },
            {

                "PostGrad": "Boston",
                "Percentage": 90,
                "subject": [{
                    "sub": "CNN",
                    "Perf": "Good"
                }],
                "Marks": [{
                    "Mark": 90,
                    "Grade": "A"
                }]
            }]
    }
}]

form this I need to fetch the sub and Mark only from the entire Json.

I got the necessary output but the concern is I have utilised multiple for loops, below mentioned is my approch to fetch sub and marks,

import json
sampleJson = open('C:\\Users\\SampleJson.json')
sampleJsonData = json.loads(sampleJson.read())

resArray=[]
for i in range(len(sampleJsonData)):
    for j in range(len(sampleJsonData[i]["Details"])):
       for k in range(len(sampleJsonData[i]["Details"]["Education"])):
           for l in range(len(sampleJsonData[i]["Details"]["Education"])):
                for y in range(len(sampleJsonData[i]["Details"]["Education"][l]["subject"])):
                    sub = (sampleJsonData[i]["Details"]["Education"][l]["subject"][y]["sub"])
                for z in range(len(sampleJsonData[i]["Details"]["Education"][l]["Marks"])):
                    marks = sampleJsonData[i]["Details"]["Education"][l]["Marks"][z]["Mark"]
                    

by any means is there any possibility that I could reduce the usage of for loops to nil.

I need to use those sub and Mark values further, as a temp measure stored the values in different variables.

I'm relatively very new to python, Please help me on this. Thanks

Answer 1

At a wild guess, it seems like you want to perform a flattening operation. Your current code definitely hasn't done it correctly, and it's not even clear what "correct" is; but if you

• replace your loads with a load;
• use a with on your file;
• get rid of all your numerical indices, and
• use a nested list comprehension on your dictionary,

you can produce a list of subject-mark tuples:

from pprint import pprint
import json

with open('272857.json') as sample_json:
    sample_json_data = json.load(sample_json)

res_array = [
    (subject['sub'], marks['Mark'])
    for person in sample_json_data
    for education in person['Details']['Education']
    for subject, marks in zip(education['subject'], education['Marks'])
]
pprint(res_array)

produces

[('Math', 90),
 ('Sci', 92),
 ('Eco', 80),
 ('Math', 100),
 ('Computers', 90),
 ('CNN', 90)]

I can only assume that it's OK for this to throw out all other information about what education and person the mark came from, etc.

[could I] reduce the usage of for loops to nil

No. Either you, or a library you call, is going to need to loop.

Answer 2

Depending on your bigger needs/situation another, completely different, approach you could take is just parse the entire string using regexp's.

So conceptually you're just looking for patterns in a string, ignoring the fact it's json, and any data structure/hierarchy contained within. However, for you needs it may fit perfectly, or it may be completely in appropriate

You could make a couple of regexps to looks for and returns the sub and mark values.

This would:

1. Not involve any loops at all
2. Therefore be much, much faster

Of course, it would also:

3. Be completely unable to handle any data grouping, hierarchy or structure
4. Be harder (somewhat) to maintain, extend or explain
5. Not as clean or simple from a code perspective

But, for you particular needs/situation/priorities this may or may not be a valid approach.