Convert the Couchbase export csv file to truly CSV file

convert.py

#!/usr/bin/env python3
import sys
import csv
import json

file = sys.argv[1]
if (not file):
    print('invalid args, need a file path')
    exit(1)

def flattenjson( b, delim ):
    val = {}
    for i in b.keys():
        if isinstance( b[i], dict ):
            get = flattenjson( b[i], delim )
            for j in get.keys():
                val[ i + delim + j ] = get[j]
        else:
            val[i] = b[i]
    return val

input = []

with open(file, 'r') as csvfile:
    reader = csv.reader(csvfile)
    next(reader, None)
    for row in reader:
        data = json.loads(row[4])
        data['id'] = row[0]
        input.append(data)

input = [ flattenjson( x, "." ) for x in input]
columns = [ x for row in input for x in row.keys() ]
columns = list( set( columns ) )
with open('out.csv', 'w') as out:
    writer = csv.writer(out)
    writer.writerow( columns )
    for i_r in input:
        writer.writerow( map( lambda x: i_r.get( x, "" ), columns ) )
print('done')