避免 Matlab 矩阵运算中的 for 循环
我有一个大的 4 维矩阵，我希望 1）找到这些维度中 2 个维度的最小值（即 4000x4000 结果），然后 2）计算最后两个维度中小于（可以说）的元素数量最小值的 5 倍（即给出的结果为 4000x4000）。我有点困惑如何在不恢复 for 循环的情况下执行此操作
一些代码可能有助于我的描述：
A = rand([4000,4000,7,7]);
B(:,:) = min(A(:,:,1:7;1:7)); % this isn't quite right?
C = size( A < 5*B ) % obviously totally wrong
任何指针都会很棒 - 非常感谢！
I have a large 4 dimensional matrix, and I wish to 1) find the minimum of 2 of those dimensions (i.e. a 4000x4000 result) and then 2) count the number of elements in those last two dimensions that are less than (lets say) 5 times the minimum (i.e giving a result of 4000x4000). I'm a bit stumped as to how to do this without reverting to for loops
Some code might aid my description:
A = rand([4000,4000,7,7]);
B(:,:) = min(A(:,:,1:7;1:7)); % this isn't quite right?
C = size( A < 5*B ) % obviously totally wrong
any pointers would be great - many thanks!
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如果我理解正确的话，以下应该可以完成这项工作：
If I understood this correctly, the following should do the job:
首先，它应该是
rand([4000,4000,7,7])其次，要使用 min，你必须执行类似
min(A, [], 1)code> （将 1 替换为尺寸）第三，假设您有
A和B，您需要C = sum(sum(A < 5*B) ）First, it should be
rand([4000,4000,7,7])Second, to use min, you have to do something like
min(A, [], 1)(replace 1 with the dimension)Third, assuming you had
AandB, you wantC = sum(sum(A < 5*B))