Python - Merge Multiple 2D Arrays with Same Dimensions into One 2d Array

Question

I have 3 2D numpy float arrays (R, G, B) with the same dimensions. I want to merge it in one 2d array, causing every element in the new 2d array to be an array of 3 floating numbers. Below is my initial code:

image = cv2.imread('hurricane katrina 1.jpg', cv2.IMREAD_GRAYSCALE)

a = 255
b = 2 * (np.pi/255)
c = np.pi / 5


R = a * np.absolute(np.sin(b * image))
G = a * np.absolute(np.sin(b * image + c))
B = a * np.absolute(np.sin(b * image + 2 * c))

How will I do it in Python without iterating through the arrays? Thanks.

UPDATE:

I want to merge the 3 Arrays. Say for example

R[0][0] = 3 
G[0][0] = 4 
B[0][0] = 6

Then the merge array will be

RGB[0][0] = (3,4,6)

And this will be true for all elements in the arrays.

So the final output shape will be (1000,775,3)

Merge and concat are literally the one and the same thing in case of numpy and lists.. — Aditya
– Aditya, Commented Apr 11, 2018 at 5:20

Aditya · Accepted Answer · 2018-04-11 05:57:57Z

2

np.concatenate((a, b,c), axis=see what you want, probably 1)

Or You can also use hstack...( They both are one and the same thing...)

Doing, rgb_transform = np.concatenate(R,G,B), throws an error. TypeError: only integer scalar arrays can be converted to a scalar index, But it shouldn't throw as I am already passing them in parenthesis

To resolve this, probably Do this np.concatenate([a, b, c], axis=see what you want, probably 1)

Refer the docs

Edit

What was asked is a bit different than above, so the correct answer is to do np.stack((r,g,b),2) as the final output is (1000,775,3)...

edited Apr 11, 2018 at 5:57

answered Apr 11, 2018 at 4:55

Aditya

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8 Comments

alyssaeliyah Over a year ago

Doing, rgb_transform = np.concatenate(R,G,B), throws an error. TypeError: only integer scalar arrays can be converted to a scalar index

Aditya Over a year ago

You are missing the extra parenthesis, they are necessary @Eliyah

Aditya Over a year ago

The first parameter to concatenate should itself be a sequence of arrays to concatenate...

alyssaeliyah Over a year ago

Thanks, I tried rgb_transform = np.concatenate([R,G,B], axis=0, out=None) and turns out working. But my problem is not address, I want to merge, not concantenate.

alyssaeliyah Over a year ago

That solves the problem. Thank you, you can edit your answer so that I can mark it right. :)

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