I have an array called n with numbers, and my goal is to make an array m where m[i] = n[i] - n[i-1]. m[0] is just equal to n[0]. I've tried this:
import numpy as np
n = np.array([1,2,3,4])
m = n
for i in range(1, len(n)):
m[i] = n[i] - n[i-1]
The assignment in the for loop does something I don't understand, because it makes both n and m into arrays = [1 1 2 2]. I simply want to change the inputs in m.
Note: My code does as I want it to when I strictly initialize both n and m like this:
n = np.array([1,2,3,4])
m = np.array([1,2,3,4])
But I feel like I should be able to make a copy of n and be able to to manipulate ONLY the copy. Any suggestions or help?
By doing m = n, you're simply binding a new name m to an existing array named n. That's why, when you later make changes to m, you see the same changes applied to n. They both refer to the same object in memory.
To make a copy of the array, you should use the numpy.copy() method:
m = np.copy(n)
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