[英]np.tile to repeat an 1D array
I have an ndarray, A
, and I want to multiply this ndarray element wise by another 1D array b
where I assume that A.shape[i] = len(b)
for some i
. 我有一个ndarray
A
,我想将此ndarray元素明智地乘以另一个1D数组b
,其中我假设A.shape[i] = len(b)
对于某些i
。 I need this generality in my application. 我的应用程序需要这种通用性。
I can do this using np.tile
as follows: 我可以使用
np.tile
做到这np.tile
,如下所示:
A = np.random.rand(2,3,5,9)
b = np.random.rand(5)
i = 2
b_shape = np.ones(len(A.shape), dtype=np.int)
b_shape[i] = len(b)
b_reps = list(A.shape)
b_reps[i] = 1
B = np.tile(b.reshape(b_shape), b_reps)
# Here B.shape = A.shape and
# B[i,j,:,k] = b for all i,j,k
This strikes me as ugly. 这让我印象深刻。 Is there a better way to do this?
有一个更好的方法吗?
For this particular example, the following code would do the trick: 对于此特定示例,以下代码可以解决问题:
result = A*b[:, np.newaxis]
For any value of i
, try this: 对于
i
任何值,请尝试以下操作:
A2, B = np.broadcast_arrays(A, b)
result = A2*B
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