Convert newline-delimited JSON (ND-JSON) to CSV

ndjson_to_csv.py

#! /usr/bin/env python3
# Usage: ndjson_to_csv <files... or stdin> > output.csv
# NB: Assumes that each line is a simple JSON object with no nested arrays or objects
import csv
import json
import sys
import fileinput
from collections import namedtuple, OrderedDict

lines = fileinput.input()
writer = csv.writer(sys.stdout)

# Preserve field order for CSV header:
first = json.loads(next(lines), object_pairs_hook=OrderedDict)
header = list(first.keys())
Row = namedtuple('Row', header)

writer.writerows([header, Row(**first)])
for row in map(json.loads, lines):
    writer.writerow(Row(**row))