Sort a csv with python from standard input

Question

This is my python script for sorting by column a csv file read from stdin:

with  sys.stdin as csvfile:
  reader = csv.reader(csvfile, delimiter=',')
  sortedlist = sorted(reader, key=operator.itemgetter(2))
  for row in sortedlist:
     print(','.join(row)),
     print('\n'),

I run the command in order to sort by 3rd column(zero indexed is 2):

./sorter1.py < test.csv > test_sorted.csv

and the sorted file test_sorted.csv is:

31,53,101,122 
88,95,103,59 
66,58,104,50 
93,46,105,52 
88,88,118,107 
**115,57,31,34** 
110,87,36,63 
32,108,36,107 
75,35,57,35 
99,46,57,28 
41,35,67,59 
108,99,98,35 
36,66,98,60

It is like sorted two files and merged it. Is it a matter of buffer size of the reader or a matter of sorted method?

This sorts alphabetically not numerically

Where was column defined and what value is it?

Moses Koledoye
– Moses Koledoye

2016-10-09 18:27:56 +00:00
Commented Oct 9, 2016 at 18:27 — Moses Koledoye
– Moses Koledoye, Commented Oct 9, 2016 at 18:27

Moses Koledoye · Accepted Answer · 2016-10-09 18:53:34Z

1

This sorts alphabetically not numerically

You'll have to cast the sort column values to integer in order to sort numerically. I have replaced the sort function with a lambda that includes the conversion to int:

sortedlist = sorted(reader, key=lambda x: int(x[2]))

answered Oct 9, 2016 at 18:53

Moses Koledoye

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