Write csv with each list as column

Question

I have a dictionary that holds a two level nested list for each key that looks like the following:

OrderedDict([(0,[['a','b','c','d'],['e','f','g','h']]), (1,[['i','j','k','l'],['m','n','o','p']])])

I would like to write each nested list to a csv as a column:

a,b,c,d      e,f,g,h
i,j,k,l      m,n,o,p

the output I am getting from my current code is:

['a','b','c','d']      ['e','f','g','h']
['i','j','k','l']      ['m','n','o','p']

The columns are correct but I would like to remove the brackets [ ] and quotes ' '

a,b,c,d      e,f,g,h
i,j,k,l      m,n,o,p

CODE:

with open('test.csv', 'w', newline='') as csv_file:
    writer = csv.writer(csv_file, quotechar='"', quoting=csv.QUOTE_ALL)
    for record in my_dict.values():
        writer.writerow(record)

Any help would be appreciated!

The data structure you listed on the first line is not valid. Can you please correct? — Trewq
– Trewq, Commented Aug 8, 2013 at 4:37

KGo · Accepted Answer · 2013-08-08 05:53:08Z

1

This should work:

with open('test.csv', 'w', newline='') as csv_file:
    writer = csv.writer(csv_file, quotechar='"', quoting=csv.QUOTE_ALL)
    for record in my_dict.values():
        final = [",".join(index) for index in record]
        writer.writerow(final)

edited Aug 8, 2013 at 5:53

answered Aug 8, 2013 at 5:31

KGo

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1 Comment

arynhard Over a year ago

works perfect, however, how would I deal with the record have 'n' number of indexes?

erewok · Accepted Answer · 2013-08-08 05:32:01Z

0

I am having trouble visualizing how your record looks because it seems like each value should be a nested list, meaning each column should contain both lists. If it were really writing one value from .values() at a time, it seems like you would get one column with both lists in it.

At any rate, what you want to achieve should probably be sought through the .join() method:

for record in my_dict.values():
    writer.writerow(','.join(record))

But the thing is, you're making a CSV (comma separated values) file, so each comma may be interpreted as a field-delimiter.

Question: Have you considered using a different delimiter when you instantiate your csv.writer?

answered Aug 8, 2013 at 5:32

erewok

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4 Comments

arynhard Over a year ago

The quoting=csv.QUOTE_ALL should quote everything written to the csv, and allow commas in the text without it being a delimiter.The record is the the entries in the OrderedDict in my post.

arynhard Over a year ago

getting TypeError: sequence item 0: expected str instance, list found from your recommended code.

KGo Over a year ago

In my answer, the loop works fine, you might need to update the parameters for the writer object though.

erewok Over a year ago

I am remembering now: it writes out the list as a row of fields. I see how you fixed it.

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