两个矩阵的列之间的交叉乘积

Question

鉴于attr_reader维度的两个矩阵和，我想计算。你能建议一种矢量化方法来进行这样的计算吗？

谢谢！

Answer 1

这是另一种方法：

np.sum(x*y, axis=0)

效率：

x = np.random.randint(0, 10, size=(30, 400))
y = np.random.randint(0, 10, size=(30, 400))

%timeit np.sum(x*y, axis=0)
# 38.4 µs ± 942 ns per loop (mean ± std. dev. of 7 runs, 10000 loops each)

%timeit for i in range(len(x.T)): x[:, i].dot(y[:, i].T)   
# 1.01 ms ± 19 µs per loop (mean ± std. dev. of 7 runs, 1000 loops each)

%timeit np.diag(x.T.dot(y))
# 6.57 ms ± 248 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)