CODEWITHSUNDEEP
pythonlistcsv
Alex Chumbley
Alex Chumbley

Reputation: 774

Writing Python lists to columns in csv

I have 5 lists, all of the same length, and I'd like to write them to 5 columns in a CSV. So far, I can only write one to a column with this code:

with open('test.csv', 'wb') as f:
    writer = csv.writer(f)
    for val in test_list:
        writer.writerow([val])

If I add another for loop, it just writes that list to the same column. Anyone know a good way to get five separate columns?

Upvotes: 50

Views: 173453

Answers (7)

Joran Beasley
Joran Beasley

Reputation: 113930

Change them to rows:

rows = zip(list1, list2, list3, list4, list5)

Then just:

import csv

with open(newfilePath, "w") as f:
    writer = csv.writer(f)
    for row in rows:
        writer.writerow(row)

Upvotes: 67

BinaryPhinary
BinaryPhinary

Reputation: 21

I just wanted to add to this one- because quite frankly, I banged my head against it for a while - and while very new to python - perhaps it will help someone else out.

 writer.writerow(("ColName1", "ColName2", "ColName"))
                 for i in range(len(first_col_list)):
                     writer.writerow((first_col_list[i], second_col_list[i], third_col_list[i]))

Upvotes: 2

Bartats
Bartats

Reputation: 21

I didn't want to import anything other than csv, and all my lists have the same number of items. The top answer here seems to make the lists into one row each, instead of one column each. Thus I took the answers here and came up with this:

import csv
list1 = ['a', 'b', 'c', 'd', 'e']
list2 = ['f', 'g', 'i', 'j','k']
with open('C:/test/numbers.csv', 'wb+') as myfile:
    wr = csv.writer(myfile)
    wr.writerow(("list1", "list2"))
    rcount = 0
    for row in list1:
        wr.writerow((list1[rcount], list2[rcount]))
        rcount = rcount + 1
    myfile.close()

Upvotes: 2

jpp
jpp

Reputation: 164613

If you are happy to use a 3rd party library, you can do this with Pandas. The benefits include seamless access to specialized methods and row / column labeling:

import pandas as pd

list1 = [1, 2, 3]
list2 = [4, 5, 6]
list3 = [7, 8, 9]

df = pd.DataFrame(list(zip(*[list1, list2, list3]))).add_prefix('Col')

df.to_csv('file.csv', index=False)

print(df)

   Col0  Col1  Col2
0     1     4     7
1     2     5     8
2     3     6     9

Upvotes: 6

shb8086
shb8086

Reputation: 31

import csv
dic = {firstcol,secondcol} #dictionary
csv = open('result.csv', "w") 
for key in dic.keys():
    row ="\n"+ str(key) + "," + str(dic[key]) 
    csv.write(row)

Upvotes: 0

Ashok Kumar Jayaraman
Ashok Kumar Jayaraman

Reputation: 3085

The following code writes python lists into columns in csv

import csv
from itertools import zip_longest
list1 = ['a', 'b', 'c', 'd', 'e']
list2 = ['f', 'g', 'i', 'j']
d = [list1, list2]
export_data = zip_longest(*d, fillvalue = '')
with open('numbers.csv', 'w', encoding="ISO-8859-1", newline='') as myfile:
      wr = csv.writer(myfile)
      wr.writerow(("List1", "List2"))
      wr.writerows(export_data)
myfile.close()

The output looks like this

enter image description here

Upvotes: 37

jh314
jh314

Reputation: 27802

You can use izip to combine your lists, and then iterate them

for val in itertools.izip(l1,l2,l3,l4,l5):
    writer.writerow(val)

Upvotes: 5

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