Is it possible to keep the column order using csv.DictReader?

Python's dicts do NOT maintain order prior to 3.6 (but, regardless, in that version the csv.DictReader class was modified to return OrderedDicts).

However, the instance of csv.DictReader that you're using (after you've read the first row!-) does have a .fieldnames list of strings, which IS in order.

So,

for rowdict in myReader:
  print ['%s:%s' % (f, rowdict[f]) for f in myReader.fieldnames]

will show you that the order is indeed maintained (in .fieldnames of course, NEVER in the dict -- that's intrinsically impossible in Python!-).

So, suppose you want to read a.csv and write b.csv with the same column order. Using plain reader and writer is too easy, so you want to use the Dict varieties instead;-). Well, one way is...:

import csv

a = open('a.csv', 'r')
b = open('b.csv', 'w')
ra = csv.DictReader(a)
wb = csv.DictWriter(b, None)

for d in ra:

  if wb.fieldnames is None:
    # initialize and write b's headers
    dh = dict((h, h) for h in ra.fieldnames)
    wb.fieldnames = ra.fieldnames
    wb.writerow(dh)

  wb.writerow(d)

b.close()
a.close()

assuming you have headers in a.csv (otherewise you can't use a DictReader on it) and want just the same headers in b.csv.

I wrote a little tool to sort the order of CSV columns: I don't claim that it's great I know little of Python, but it does the job:

import csv
import sys

with open(sys.argv[1], 'r') as infile:
    csvReader = csv.DictReader(infile)
    sorted_fieldnames = sorted(csvReader.fieldnames)
    writer = csv.DictWriter(sys.stdout, fieldnames=sorted_fieldnames)
    # reorder the header first
    writer.writeheader()
    for row in csvReader:
        # writes the reordered rows to the new file
        writer.writerow(row)