How can I multiply all the elements in a list with a given constant?

Question

 [[[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0,-7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0,-7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]]]

I want to multiply all the numbers in this list using Python with a constant (say (-1)), but the list still has the original format. I was trying to do that with 3 'for' loops, but is there a short way I can do this? Thanks!!

score 3 · Accepted Answer · answered Aug 17 '20 at 20:25

3

The following code can multiply all of the numbers by a constant. For more advanced operations, you may want to look into np.vectorize or np.apply

import numpy as np

nested_list = [[[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0,-7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0,-7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]], [[-7.0, -7.0], [-7.0, -7.0], [-7.0, -7.0]]]
numpy_list = np.array(nested_list)

negated_list = -1 * numpy_list

answered Aug 17 '20 at 20:25

Andrew Mascillaro

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Thanks! That really helps:) – ZR- Aug 17 '20 at 20:41
1

If this was helpful to you, can you upvote the answer and accept it? I'm glad it worked for you. – Andrew Mascillaro Aug 17 '20 at 20:42
I've upvoted but I don't have enough point to make it appear. Thanks!! – ZR- Aug 17 '20 at 21:28
@Zhengrong. You do now – Mad Physicist Aug 17 '20 at 21:46
Oh great! Thanks:) – ZR- Aug 18 '20 at 01:10

How can I multiply all the elements in a list with a given constant?

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