Writing to CSV with Python adds blank lines

76
votes

I am trying to write to CSV file but there are blank rows in between. How can I remove the blank rows?

import csv
b = open('test.csv', 'w')
a = csv.writer(b)
data = [['Me', 'You'],\
        ['293', '219'],\
        ['54', '13']]
a.writerows(data)
b.close()
5
pythoncsvpython-3.3
You don't need backslashes at the end of the lines defining data. Python ignores newlines inside the enclosing square brackets, i.e. between [ and ] - Zags
Correct me if I am wrong but that backslash is the continuation character, isnt it not? - KennethG
This is old, but I noticed no one responded. The continuation character is not needed if you have a comma. - gprx100
See also: How do I read and write CSV files with Python? - Martin Thoma

5 Answers

117
votes

The way you use the csv module changed in Python 3 in several respects (docs), at least with respect to how you need to open the file. Anyway, something like

import csv
with open('test.csv', 'w', newline='') as fp:
    a = csv.writer(fp, delimiter=',')
    data = [['Me', 'You'],
            ['293', '219'],
            ['54', '13']]
    a.writerows(data)

should work.

21
votes

If you're using Python 2.x on Windows you need to change your line open('test.csv', 'w') to open('test.csv', 'wb'). That is you should open the file as a binary file.

However, as stated by others, the file interface has changed in Python 3.x.

15
votes
import csv

hello = [['Me','You'],['293', '219'],['13','15']]
length = len(hello[0])

with open('test1.csv', 'wb') as testfile:
    csv_writer = csv.writer(testfile)
    for y in range(length):
        csv_writer.writerow([x[y] for x in hello])

will produce an output like this

Me You
293 219
13 15

Hope this helps

5
votes

You need to open the file in binary b mode to take care of blank lines in Python 2. This isn't required in Python 3.

So, change open('test.csv', 'w') to open('test.csv', 'wb').

3
votes

Pyexcel works great with both Python2 and Python3 without troubles.

Fast installation with pip:

pip install pyexcel

After that, only 3 lines of code and the job is done:

import pyexcel
data = [['Me', 'You'], ['293', '219'], ['54', '13']]
pyexcel.save_as(array = data, dest_file_name = 'csv_file_name.csv')