Python 无法将输入数组从形状 (3,1) 广播到形状 (3,)
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Can't broadcast input array from shape (3,1) into shape (3,)
提问by Colin
import numpy as np
def qrhouse(A):
(m,n) = A.shape
R = A
V = np.zeros((m,n))
for k in range(0,min(m-1,n)):
x = R[k:m,k]
x.shape = (m-k,1)
v = x + np.sin(x[0])*np.linalg.norm(x.T)*np.eye(m-k,1)
V[k:m,k] = v
R[k:m,k:n] = R[k:m,k:n]-(2*v)*(np.transpose(v)*R[k:m,k:n])/(np.transpose(v)*v)
R = np.triu(R[0:n,0:n])
return V, R
A = np.array( [[1,1,2],[4,3,1],[1,6,6]] )
print qrhouse(A)
It's qr factorization code, but I don't know why error happens.
The value error happens in V[k:m,k] = v
这是 qr 分解代码，但我不知道为什么会发生错误。值错误发生在V[k:m,k] = v
value error :
could not broadcast input array from shape (3,1) into shape (3)
回答by hpaulj
V[k:m,k] = v; vhas shape (3,1), but the target is (3,). k:mis a 3 term slice; kis a scalar.
V[k:m,k] = v; v具有形状 (3,1)，但目标是 (3,)。k:m是 3 项切片；k是一个标量。
Try using v.ravel(). Or V[k:m,[k]].
尝试使用v.ravel(). 或者V[k:m,[k]]。
But also understand why vhas its shape.
但也明白为什么v会有它的形状。
回答by Daniel Peterson
Another solution that would work is V[k:m,k:k+1] = v.
另一个可行的解决方案是V[k:m,k:k+1] = v.
k:k+1is a 1 term slice, making the target shape (3,1).
k:k+1是 1 项切片，使目标形状 (3,1)。
This seems like a better solution since you do not have to modify the input array.
这似乎是一个更好的解决方案，因为您不必修改输入数组。
回答by ChaosPredictor
Other way to do it is by transpose:
另一种方法是通过转置：
V[k:m,k] = v.transpose()
