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])