fill.py

#!/usr/bin/env python2
# -*- coding: iso-8859-1 -*-

import csv
import io
import sys

CSV_INPUT_PATH = "Z:\\extracted.csv"

COLUMN_C = "TIMES FIVE"
COLUMN_D = "PLUS THOUSAND"

CSV_OUTPUT_PATH = "Z:\\enriched.csv"

# The following can be a complex function,
# somehow computing two numbers from two numbers.
def compute_new_data(old_row):
  return [float(old_row[0]) * 5, float(old_row[1]) + 1000]

# Open the standard input stream as a CSV file.
csv_input = open(CSV_INPUT_PATH)
reader = csv.reader(csv_input)
old_names = next(reader)

# Open the standard output stream as a CSV file.
csv_output = open(CSV_OUTPUT_PATH, "wb")
writer = csv.writer(csv_output)

# Read one line of the input CSV file at a time,
# and enrich this line with computations
# from our above complex function,
# then write the enriched line into the output CSV file.
writer.writerow(old_names + [COLUMN_C, COLUMN_D])
for old_row in reader:
  node_label = old_row[0]
  new_row = compute_new_data(old_row[1:])
  writer.writerow(old_row + new_row)

csv_output.close()
csv_input.close()