When running code. I got error. ValueError: operands could not be broadcast together with remapped shapes [original->remapped]: (1000,) and requested shape (1000,1)

If you change ax.plot by ax.scatter it should work

Could you please explain why deltas need to be scaled? Without that the results are totally wrong...

i think that xs and zs should be reshaped too: ax.plot(xs.reshape(observations,), zs.reshape(observations,), targets)