Writing a Python list of lists to a csv file

192

I have a long list of lists of the following form ---

a = [[1.2,'abc',3],[1.2,'werew',4],........,[1.4,'qew',2]]

i.e. the values in the list are of different types -- float,int, strings.How do I write it into a csv file so that my output csv file looks like

1.2,abc,3
1.2,werew,4
.
.
.
1.4,qew,2

This question is tagged with python file csv file-io python-2.7

~ Asked on 2012-12-26 07:43:47

The Best Answer is


334

Python's built-in CSV module can handle this easily:

import csv

with open("output.csv", "wb") as f:
    writer = csv.writer(f)
    writer.writerows(a)

This assumes your list is defined as a, as it is in your question. You can tweak the exact format of the output CSV via the various optional parameters to csv.writer() as documented in the library reference page linked above.

Update for Python 3

import csv

with open("out.csv", "w", newline="") as f:
    writer = csv.writer(f)
    writer.writerows(a)

~ Answered on 2012-12-26 07:46:09


37

You could use pandas:

In [1]: import pandas as pd

In [2]: a = [[1.2,'abc',3],[1.2,'werew',4],[1.4,'qew',2]]

In [3]: my_df = pd.DataFrame(a)

In [4]: my_df.to_csv('my_csv.csv', index=False, header=False)

~ Answered on 2015-01-22 19:42:07


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