Given parameters

timestep = 2
window_size = 3

I have flatenned vector of timeseries with size 9.
The content is:

arr = np.array([1,2,3,4,5,6,7,8,9])

How to reshape/construct windowed timeseries with those parameters?

I expect the output will having shape

unknown, window_size)

So, its output would be matrix like this:

windowed_arr = np.array([
  [1,2,3],
  [3,4,5],
  [5,6,7],
  [7,8,9]
  ])