CODEWITHSUNDEEP
python
JodeCharger100
JodeCharger100

Reputation: 1059

Subtract a different number from each column in an array

Assuming I have the following array in Python:

x = np.array(([1,2,3,4],[5,6,7,8],[9,10,11,12]))
x

Which looks like:

array([[ 1,  2,  3,  4],
       [ 5,  6,  7,  8],
       [ 9, 10, 11, 12]])

I have an array mu, which is the mean of each of the columns of array x

mu = x.mean(axis =0)

Which looks like:

array([5., 6., 7., 8.])

Now, I want a new array x_demean, where the first column gets subtracted by its own mean, second column by its own mean, and so one. The result should look like:

array([[ -4,  -4,  -4,  -4],
       [ 0,  0,  0,  0],
       [ 4,  4,  4,  4])

Upvotes: 2

Views: 181

Answers (2)

amrs-tech
amrs-tech

Reputation: 483

You can use simple x - mu which provides the desired output.

You can use the proper subtract() method of numpy also. Refer the docs here.

Try this code:

import numpy as np

x1 = np.array(([1,2,3,4],[5,6,7,8],[9,10,11,12]))
mu = x1.mean(axis =0)
x_demean = np.subtract(x1, mu)
print(x_demean) #use x_demean.astype(int) if you want integer array

Upvotes: 2

moys
moys

Reputation: 8033

x-mu is all you need to get what you want.

If you want output strictly as integers, do (x-mu).astype(int)

Output

array([[-4, -4, -4, -4],
       [ 0,  0,  0,  0],
       [ 4,  4,  4,  4]])

Upvotes: 3

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