sort csv by column

Question

Hi!

I want to sort a CSV table by date. Started out being a simple task:

import sys
import csv

reader = csv.reader(open("files.csv"), delimiter=";")

for id, path, title, date, author, platform, type, port in reader:
    print date

I used Python's CSV module to read in a file with that structure:

id;file;description;date;author;platform;type;port

• The date is ISO-8601, therefore I can sort it quite easily without parsing: 2003-04-22 e. g.
• I want to sort the by date, newest entries first
• How do I get this reader into a sortable data-structure? I think with some effort I could make a datelist: datelist += date, split and sort. However I have to re-identify the complete entry in the CSV table. It's not just sorting a list of things.
• csv doesn't seem to have a built in sorting function

The optimal solution would be to have a CSV client that handles the file like a database. I didn't find anything like that.

I hope somebody knows some nice sorting magic here ;)

Thanks,

Marius

Answer 1

sortedlist = sorted(reader, key=operator.itemgetter(3), reverse=True)

Answer 2

You do realize that the reader acts like a generator? On a file with some fake data:

>>> import sys, csv
>>> data = csv.reader(open('data.csv'),delimiter=';')
>>> data
<_csv.reader object at 0x1004a11a0>
>>> data.next()
['a', ' b', ' c']
>>> data.next()
['x', ' y', ' z']
>>> data.next()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration

Using operator.itemgetter as Ignacio suggests:

>>> data = csv.reader(open('data.csv'),delimiter=';')
>>> import operator
>>> sortedlist = sorted(data, key=operator.itemgetter(2), reverse=True)
>>> sortedlist
[['x', ' y', ' z'], ['a', ' b', ' c']]