Write to csv with columns as list in python?

Question

I have a list that looks like:

[('CarrierDel', '1973.0', '4227.0', '518.0', '2701.0', '3249.0', '7354.0', '980.0', '428.0', '394.0'), ('CarrierID', '9E', 'AA', 'AS', 'B6', 'DL', 'EV', 'F9', 'FL', 'HA'), ('Delays', '3626.0', '8394.0', '1071.0', '3880.0', '5927.0', '13836.0', '1461.0', '1254.0', '303.0')]

where 'CarrierDel', 'CarrierID' and 'Delays' are my headers. I want to write this to a csv file. Is there an equivalent to writerow but for columns? Or is there another way to go about this?

Thanks!

You could compile the three together making rows instead of columns e.g. change what you supplied to something like [('CarrierDel', 'CarrierID', 'Delays')...] and so on. Something like a matrix transpose. — PurityLake
– PurityLake, Commented Nov 14, 2013 at 17:00

Joran Beasley · Accepted Answer · 2013-11-14 16:57:24Z

4

import csv
w = csv.writer(open("some_file.txt","w"))
w.writerows(zip(*list_of_cols))

should do it

zip transposes a 2d array(among other things) as seen below

 a = [[1,2,3],[4,5,6],[7,8,9]]
 #transpose a with zip
 print zip(*a)  #prints [(1,4,7),(2,5,8),(3,6,9)]

edited Nov 14, 2013 at 16:57

answered Nov 14, 2013 at 16:48

Joran Beasley

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3 Comments

marc Over a year ago

So that does work for me. But how come when I use with open(output.csv, 'w') as ouput: it separates each item in the csv file?

marc Over a year ago

Sorry I'll try to clarify. When I use exactly what you gave me, it works np. When I try using with open('output.csv', 'w')... my output looks like "['CarrierDel', 'CarrierID', 'Delays']","['1973.0', '9E', '3626.0']","['4227.0', 'AA', '8394.0']","['518.0', 'AS', '1071.0']","['2701.0', 'B6', '3880.0']","['3249.0', 'DL', '5927.0']","['7354.0', 'EV', '13836.0']","['980.0', 'F9', '1461.0']","['428.0', 'FL', '1254.0']","['394.0', 'HA', '303.0']"

Joran Beasley Over a year ago

no you need to use the csv module ... or manually manage your array ... you cant just write it to a file ...

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