python - Numpy difference between neighboring elements

Question

I have algorithm of calculation of the difference between neighboring elements in pure python:

    a = range(1000000) #it's numpy array in my case
    prev = a[0]
    b = [0, ]
    for i in a[1:]:
        b.append(i - prev)
        prev = i

Is there any way to rewrite this functions with Numpy?

Answer 1

There is the diff method:

a = range(5) # python list of numpy array
np.diff(a)

returns

array([1, 1, 1, 1])