Thanks very much. It works. On Mon, Mar 7, 2011 at 11:53 AM, <qu...@gmx.at> wrote:
> for your problem, you can do: > > ---------------------------- > > import numpy as np > > weights = np.array([1,2]) > > matrix1 = np.ones((2,3)) > matrix2 = 2*np.ones((2,3)) > > matrices = np.array([matrix1,matrix2]) > > weighted_sum = np.tensordot(weights, matrices, (0,0)) > > -------------------------- > > On Mon, Mar 07, 2011 at 06:16:15AM -0600, shu wei wrote: > > Hello all, > > > > I am new to python and numpy. > > My question is how to sum up N weighted matrices. > > For example w=[1,2] (N=2 case) > > m1=[1 2 3, > > 3 4 5] > > > > m2=[3 4 5, > > 4 5 6] > > I want to get a matrix Y=w[1]*m1+w[2]*m2 by using a loop. > > > > My original problem is like this > > X=[1 2 3, > > 3 4 5, > > 4 5 6] > > > > a1=[1 2 3] 1st row of X > > m1=a1'*a1 a matirx > > a2=[3 4 5] 2nd row of X > > m2=a2'*a2 > > a3=[ 4 5 6] 3rd row of X > > m3=a3'*a3 > > > > I want to get Y1=w[1]*m1+w[2]*m2 > > Y2=w[1]*m2+w[2]*m3 > > So basically it is rolling and to sum up the weighted matries > > I have a big X, the rolling window is relatively small. > > > > I tried to use > > > > sq=np.array([x[i].reshape(-1,1)*x[i] for i in np.arange(0,len(x)]) # > > s=len(x) > > m=np.array([sq[i:i+t] for i in np.arange(0,s-t+1)]) # t is the len(w) > > > > then I was stuck, I tried to use a loop somethig like > > Y=np.array([np.sum(w[i]*m[j,i],axis=0) for i in np.arange(0,t)] ) > > Any suggestion is welcome. > > > > sue > > > _______________________________________________ > > NumPy-Discussion mailing list > > NumPy-Discussion@scipy.org > > http://mail.scipy.org/mailman/listinfo/numpy-discussion > > > -- > There are two things children should get > from their parents: roots and wings. > > The king who needs to remind his people of his rank, is no king. > > A beggar's mistake harms no one but the beggar. A king's mistake, > however, harms everyone but the king. Too often, the measure of > power lies not in the number who obey your will, but in the number > who suffer your stupidity. > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion >
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