Numpy按行索引修改行

Question

我想修改(在这种情况下否定)给定索引的矩阵的几行，并保持其他行不变。

A = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
indices = np.array([1, 2])
A_ = np.array([[1, 2, 3], [-4, -5, -6], [-7, -8, -9]])

从A和索引中获得A_的最快方法是什么?

Answer 1

with for loop

for i in indices:
A[i] *=-1

与屏蔽

A[indices] *= -1