Reading File into Python Dictionary and then Writing to File

Question

I have aa multi-row, multi-column text file. Has a header if that's important. Want to read all the data into a Python dictionary and then just write it out again in a file. I ultimately want to create two dictionaries from two file, join them on the key, and then print out the joined version but I can't even get this part right. This is what I got:

import sys
import csv
from collections import defaultdict

usage = "usage: python Newer.py <project_file> <table_file> <outfile>"
if len(sys.argv) != 4:
    print usage
    sys.exit(0)

project = open(sys.argv[1], "rb")
table = open(sys.argv[2], "rb")
outfile = open(sys.argv[3], "w")

projectdict = defaultdict(list)

for line in project:
    parts = line.strip().split("\t")
    first = parts[1]
    projectdict[first].append(line)

for key in projectdict:
    outfile.write(" ".join(projectdict[first]) + "\n")

And what I get from it is a text file with the same entry from the text file repeated over and over again.

Answer 1

The issue is that you're writing the value at key "first" every time in the second loop, regardless of what the actual key is. I believe this will fix your problem.

for key in projectdict:
    outfile.write(" ".join(projectdict[key]) + "\n")