Write a 2D array to a CSV file in python

Question

I have a 2D array from a function f.example which returns me:

array([[ 0.0, 1.0, 2.0, 3.0 ],
       [ 5.0, 1.0, 3.0, 3.0 ],
       [ 1.0, 1.0, 3.0, 3.0 ]])

In fact I am able to write it to a csv file, but just not the way I want. Here is how the csv file should look like:

0.0 5.0 1.0
1.0 1.0 1.0
2.0 3.0 3.0
3.0 3.0 3.0

But this is how it looks now:

0.0 1.0 2.0 3.0
5.0 1.0 3.0 3.0
1.0 1.0 3.0 3.0

And the code that I have:

with open('example.csv', 'w') as csvfile:
    writer = csv.writer(csvfile)
    writer.writerows(f.example)

Transpose the matrix before writing it out

Jiří Baum
– Jiří Baum

2021-06-22 08:32:57 +00:00
Commented Jun 22, 2021 at 8:32 — Jiří Baum
– Jiří Baum, Commented Jun 22, 2021 at 8:32

Daweo · Accepted Answer · 2021-06-22 08:26:13Z

3

You need to transpose your array first

import numpy as np
arr = np.array([[0.0, 1.0, 2.0, 3.0],[5.0, 1.0, 3.0, 3.0],[1.0, 1.0, 3.0, 3.0 ]])
arr_t = arr.T
print(arr_t)

output

[[0. 5. 1.]
 [1. 1. 1.]
 [2. 3. 3.]
 [3. 3. 3.]]

Then follows as earlier.

answered Jun 22, 2021 at 8:26

Daweo

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leaf_soba · Accepted Answer · 2021-06-22 08:31:24Z

2

if you can't use numpy

code:

import csv
x = [[ 0.0, 1.0, 2.0, 3.0 ],
    [ 5.0, 1.0, 3.0, 3.0 ],
    [ 1.0, 1.0, 3.0, 3.0 ]]
with open('example.csv', 'w') as csvfile:
    writer = csv.writer(csvfile)
    writer.writerows(list(zip(*x)))

result:

0.0,5.0,1.0

1.0,1.0,1.0

2.0,3.0,3.0

3.0,3.0,3.0

answered Jun 22, 2021 at 8:31

leaf_soba

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1 Comment

Emotional Damage Over a year ago

Thanks @leaf_yakitori, both the answers helped!

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