tempfile_truncate_test.py

#!/usr/bin/env python

import tempfile
import shutil

"""
Here is a test I created to recreate a problem I was having when I used
tempfile.NamedTemporaryFile(). The problem is that when I use tempfile my
data in my CSV is truncated off the end of the file.

When you run this test script, temp2.csv will get truncated and temp1.csv
will be the same size as the original CSV.

I'm using Python 2.7.1.

You can download the sample CSV from http://explore.data.gov/Energy-and-Utilities/Residential-Energy-Consumption-Survey-RECS-Files-A/eypy-jxs2
"""


def main():
    f = open('RECS05alldata.csv')
    data = f.read()
    f.close()

    f = open('temp1.csv', 'w+b')
    f.write(data)
    f.close()

    temp = tempfile.NamedTemporaryFile()
    temp.write(data)
    shutil.copy(temp.name, 'temp2.csv')
    temp.close()

if __name__ == '__main__':
    main()