Python – How to write two lists of different lengths to columns and rows in a csv file

I have two lists of different lengths:

list1 = ['a']
list2 = [['apple','banana','grapes']]

The csv I want is the following:

col1  col2
a     apple, banana, grapes

So first I tried itertool and izip, but it seems to only put the first element of the list in list2 of col2, so it looks like :

col1  col2
a     apple

How to get the version above, with the full list in list2 as rows?

I used the following code to store the above to csv:

import csv
from itertools import izip

with open('some.csv', 'wb') as f:
    writer = csv.writer(f)
    writer.writerows(izip(list1,sum(list2,[]))

izip truncates longer lists to match shorter lists, so izip([‘a’], [‘a’, ‘b’, ‘c’]) actually gives [‘a’, 'a'], which is where the problem comes from.

Also, usually you will want to use str.join() instead of sum() to convert the list to a string.

Based on this question, I guess you want a CSV file delimited by tabs. To solve the problem, first convert list2 to a string list:

    >>> list2_str = [','.join(lst) for lst in list2]
    ['apple,banana,grapes']

Then compress list1 and list2_str:

    >>> list3 = zip(list1, list2_str)
    [['a', 'apple,banana,grapes']]

Open a csv writer in the “excel-tab” dialect and write the line:

    >>> writer = csv.writer(file, dialect='excel-tab')
    >>> writer.writerows(list3)

If you want a csv file delimited by “,”, just remove the dialect parameter. Python will correctly reference the second column, generated

    a,"apple,banana,grapes"

In a CSV file.