from sklearn.preprocessing import OneHotEncoder
encoder = preprocessing.OneHotEncoder(handle_unknown='ignore')
y = np.array([1, 2, 1, 3])
y = y.reshape(-1,1)
encoder.fit(y)
y_oh = encoder.transform(y).toarray()
print(y_oh)
>>[[1. 0. 0.]
 [0. 1. 0.]
 [1. 0. 0.]
 [0. 0. 1.]]