Finding False-True transitions in a numpy array

Question

Given a numpy array:

x = np.array([False, True, True, False, False, False, False, False, True, False])

How do I find the number of times th

Answer 1

I kind of like to use numpy method "roll" for this kind of problems... "roll" rotates the array to left some step length : (-1,-2,...) or to right (1,2,...)

import numpy as np
np.roll(x,-1)

...this will give x but shifted one step to the left:

array([ True,  True, False, False, False, False, False,  True, False, False], 
dtype=bool)

A False followed by a True can then be expressed as:

~x & np.roll(x,-1)

array([ True, False, False, False, False, False, False,  True, False, False], 
dtype=bool)