On Fri, Nov 18, 2016 at 6:51 PM, <limetree...@gmail.com> wrote: > Hi :) > I'm trying to multiply two matrices that has different size. > > -------------------------------------code------------------------- > > import numpy as np > > a = np.random.randn(4, 3) > b = np.random.randn(4, 1) > > print a > print b > > -------------------------------------code------------------------- > > How should I multiply a and b so that the multipled matrix's size is 4*3? > > I want to multiply matrix 'b' to each row of matrix 'a'. > So that if matrix a is > [[1, 2, 3], > [2, 3, 4]] > and b is > [[2], > [3]] > a*b is > [[2, 4, 6], > [4, 6 ,8]] > > Plz help me! > > if possible, plz use numpy
You don't need to do anything special. >>> import numpy as np >>> a = np.array([[1,2,3],[2,3,4]]) >>> b = np.array([[2], [3]]) >>> a array([[1, 2, 3], [2, 3, 4]]) >>> b array([[2], [3]]) >>> a * b array([[ 2, 4, 6], [ 6, 9, 12]]) (I'm assuming this is actually the output you want. The output you posted is jut a * 2.) -- https://mail.python.org/mailman/listinfo/python-list