Convert array of indices to 1-hot encoded numpy array

Question

I want to encode a 1-D numpy array:

x = array([1,0,3]) 

 As a 2-D 1-hot array

y = array([[0,1,0,0], [1,0,0,0], [0,0,0,1]])

Suggest me some faster technique other than looping. 

Answer 1

@Anisha, Refer to the following code it may help.

>>> x = [1, 0, 3]

>>> z = np.max(x) + 1

>>> np.eye(z)[x]

array([[ 0.,  1., 0., 0.],

      [ 1., 0.,  0., 0.],

      [ 0., 0.,  0., 1.]])

Alernatively, you can use:

>>> x = np.array([1, 0, 3])

>>> z= np.zeros((3, 4))

>>> z[np.arange(3), x] = 1

>>> y

array([[ 0.,  1., 0., 0.],

      [ 1., 0.,  0., 0.],

      [ 0., 0.,  0., 1.]])