防止 Python 中的 for 循环求和 function

Question

I have a vector x of length 10 . I want to perform the following summation in Python:

sum |x_{i} - x_{i-1}| over all i

I have written the below code, but I am sure there is a more optimal way in order to prevent the for loop. I need your suggestions.

import numpy as np
x = np.random.rand(10,1)
sum = 0 

#note that in Python the index starts at 0
for i in range(10-1): 
    sum = sum + abs(x[i+1] - x[i])

Any help will be very appreciated!

Answer 1

Sure, you can do something like:

np.abs(x[1:] - x[:-1]).sum()

Also, if you need to maintain the result as a vector, you can use:

np.abs(x[1:] - x[:-1]).sum(axis=0)