Numpy: Divide each row by a vector element

Question

Suppose I have a numpy array:

data = np.array([[1,1,1],[2,2,2],[3,3,3]])

and I have a corresponding \"vector:\"

vector = np         


        

Answer 1

As has been mentioned, slicing with None or with np.newaxes is a great way to do this. Another alternative is to use transposes and broadcasting, as in

(data.T - vector).T

and

(data.T / vector).T

For higher dimensional arrays you may want to use the swapaxes method of NumPy arrays or the NumPy rollaxis function. There really are a lot of ways to do this.

For a fuller explanation of broadcasting, see http://docs.scipy.org/doc/numpy/user/basics.broadcasting.html