[英]theano: row-wise outer product between two matrices
I'm trying to compute the row-wise outer-product between two matrices in theano, without using scan. 我试图不使用扫描来计算theano中两个矩阵之间的按行外积。 I can do this in numpy by using einsum, which isn't available in theano. 我可以使用einsum在numpy中完成此操作,而theano则不可用。
A = np.array([[1,1,1],[2,2,2]])
B = np.array([[3,3,3,3],[4,4,4,4]])
print np.einsum('xi,xj->xij', A, B)
[[[3 3 3 3]
[3 3 3 3]
[3 3 3 3]]
[[8 8 8 8]
[8 8 8 8]
[8 8 8 8]]]
This should be doable using some reshaping: Many of the simple einsum operations boil down to that. 这可以通过重塑来实现:许多简单的einsum操作可以归结为这一点。 The complicated ones don't. 复杂的没有。
import theano
import theano.tensor as T
import numpy as np
a = np.array([[1,1,1],[2,2,2]]).astype('float32')
b = np.array([[3,3,3,3],[4,4,4,4]]).astype('float32')
A = T.fmatrix()
B = T.fmatrix()
C = A[:, :, np.newaxis] * B[:, np.newaxis, :]
print C.eval({A:a, B:b})
results in 结果是
[[[ 3. 3. 3., 3.]
[ 3. 3. 3., 3.]
[ 3. 3. 3.. 3.]]
[[ 8. 8. 8., 8.]
[ 8. 8. 8., 8.]
[ 8. 8. 8., 8.]]]
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