How to write nested dictionaries to a CSV file

Question

I am facing difficulty in writing a nested dictionary to a CSV file. Below is the dictionary: Score = {'Student-1': {'1st Term': 0, '2nd Term': 0, '3rd Term': 0, '4th Term': 0}, 'ge60le90': {'1st Term': 4, '2nd Term': 0, '3rd Term': 0, '4th Term': 0}, 'gt90': {'1st Term': 0, '2nd Term': 1, '3rd Term': 2, '4th Term': 1} } I want to write this dictionary in a CSV format, consider the below example:

Answer 1

You can use Pandas Module, consider the code below:
import pandas as pd

Score = {'Student-1': {'1st Term': 0, '2nd Term': 0, '3rd Term': 0, '4th Term': 0}, 'Student-2': {'1st Term': 4, '2nd Term': 0, '3rd Term': 0, '4th Term': 0}, 'Student-3': {'1st Term': 0, '2nd Term': 1, '3rd Term': 2, '4th Term': 1} }

df = pd.DataFrame(Score)

df = df.rename(columns={'Student-1': 'Good',
'Student-2': 'Medium',
'Student-3': 'Bad'})

df.to_csv('student.csv', index=False)

Answer 2

import csv
import itertools
import sys

fields = [ 'org', '2015', '2014', '2013' ]
dw     = { 'orgname1': { '2015' : 2, '2014' : 1, '2013' : 1 },
           'orgname2': { '2015' : 1, '2014' : 2, '2013' : 3 },
           'orgname3': { '2015' : 1, '2014' : 3, '2013' : 1 }
        }

w = csv.DictWriter( sys.stdout, fields )
for key,val in sorted(dw.items()):
    row = {'org': key}
    row.update(val)
    w.writerow(row)

Answer 3

import csv
import itertools

fields = [ 'org', '2015', '2014', '2013' ]
dw     = { 'orgname1': { '2015' : 2, '2014' : 1, '2013' : 1 },
           'orgname2': { '2015' : 1, '2014' : 2, '2013' : 3 },
           'orgname3': { '2015' : 1, '2014' : 3, '2013' : 1 }
        }

with open("test_output.csv", "wb") as f:
    w = csv.DictWriter(f, fields)
    w.writeheader()
    for k in dw:
        w.writerow({field: dw[k].get(field) or k for field in fields})

Output:

org,2015,2014,2013
orgname1,2,1,1
orgname3,1,3,1
orgname2,1,2,3

Comments

If the value is 0 it is replacing the value 0 with the 'org' value.

Use this data set to test it:

dw     = { 'orgname1': { '2015' : 0, '2014' : 0, '2013' : 1 },
           'orgname2': { '2015' : 1, '2014' : 0, '2013' : 3 },
           'orgname3': { '2015' : 1, '2014' : 3, '2013' : 1 }
        }

Answer 4

Using DictWriter there is no need in sorting the fields in advance, since w.writerow() will assure the correct order. But it does make sense to sort the items themselves.

So putting together all the above suggestions and picking the best of each, i would come up with following code:

import csv
import itertools

def mergedict(a,b):
    a.update(b)
    return a

fields = [ 'org', '2015', '2014', '2013' ]
dw     = { 'orgname1': { '2015' : 2, '2014' : 1, '2013' : 1 },
           'orgname2': { '2015' : 1, '2014' : 2, '2013' : 3 },
           'orgname3': { '2015' : 1, '2014' : 3, '2013' : 1 }
        }

with open("test_output.csv", "wb") as f:
    w = csv.DictWriter( f, fields )
    w.writeheader()
    for k,d in sorted(dw.items()):
        w.writerow(mergedict({'org': k},d))