How can I write a zero-array in a csv file in python?

Question

I would like to write a csv file in Python 3 with the following format: "index, 0". E.g.:

0, 0

1, 0

2, 0

3, 0

...

I have written the following:

csv_file_object = csv.writer(open('file.csv', 'w', newline='')) 
Y=np.zeros(2508, dtype=int)
for index, y_aux in enumerate(Y):      
    csv_file_object.writerow([index, y_aux])

However, when I have opened the csv file, I can see:

0

1

2

3

...

How can I solve this? Thank you.

Does writing csv_file_object.writerow([index, str(y_aux)]) solve your problem? — CakePlusPlus
– CakePlusPlus, Commented Nov 3, 2017 at 19:19
What tool did you use to open the csv file? I can't reproduce your results. — Robᵩ
– Robᵩ, Commented Nov 3, 2017 at 19:23
Can you help us to understand your actual goal here? Are you trying to create a file with the indicated content? Or are you trying write an np.ndarray to a file, adding an index? To put it another way, is numpy an essential element of the solution? — Robᵩ
– Robᵩ, Commented Nov 3, 2017 at 19:37

Thomas Junk · Accepted Answer · 2017-11-03 19:23:49Z

1

This gets the desired output:

import csv

with open("my.csv", "w") as out:
    writer = csv.writer(out, delimiter=",")
    for i in xrange(1,10):
        writer.writerow([i,0])

But I don't know, what np.zeros(2508, dtype=int) is. Perhaps you elaborate a bit on your question.

answered Nov 3, 2017 at 19:23

Thomas Junk

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2 Comments

Robᵩ Over a year ago

np.zeroes is probably from import numpy as np.

Thomas Junk Over a year ago

@Robᵩ sounds good, but I haven't worked with numpy ;) so I can not confirm

hussam · Accepted Answer · 2017-11-03 19:38:52Z

0

It is not necessary to play with file i/o
There's an easier way

import numpy as np
import pandas as pd

mypath='your path here'

Y=np.zeros(2508, dtype=int)

convert to a pandas dataframe

U=pd.DataFrame(Y, columns=['zeros'])

U.head()     

    zeros
0   0
1   0
2   0
3   0
4   0

save directly to .csv

U.to_csv(mypath+'U.csv')

edited Nov 3, 2017 at 19:38

answered Nov 3, 2017 at 19:24

hussam

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