Construct two dimensional numpy array from indices and values of a one dimensional array

Question

Say I\'ve got

Y = np.array([2, 0, 1, 1])

From this I want to obtain a matrix X with shape (len(Y), 3). In this particular cas

Answer 1

Y = np.array([2, 0, 1, 1])
new_array = np.zeros((len(Y),3))
for i in range(len(Y)):
    new_array[i,Y[i]] = 1

I think ... i dont think there is an easier way (but i might be wrong)