Question

我需要对以下matlab代码进行矢量化，现在对于更大的矩阵A和多重向量m来说速度很慢：

function cA = condenseM(A,m)
% condensation of full matrix A (MxM) to type matrix (MxT)
% m is vector of type multiplicities [m1, ...,mT], where 
% M = sum(m) 

% M,T
M = sum(m);
T = length(m);

% "0" + last item index over all types
blockTypeIndx = [0 cumsum(m)];

% condensed matrix generation
cA = zeros(M,T);
for i = 1:T
    if m(i) > 1
       cA(:,i) = max(A(:,blockTypeIndx(i)+1:blockTypeIndx(i+1)),[],2);
    else
       cA(:,i) = A(:,blockTypeIndx(i)+1:blockTypeIndx(i+1));
    end
end
end

对于矩阵A（6x6），这是一个简单且通用的示例案例：

 A =

 0     3     3   |  1     1  |   6
 4     0     0   |  0     0  |   2
 0     0     0   |  5     0  |   0
 0     1     1   |  4     4  |   1
 2     0     0   |  0     0  |   5
 0     0     0   |  0     3  |   0
       m1=3          m2 = 2     m3=1

T = 3的多重向量m：

 m =
 3     2     1

浓缩矩阵cA看起来像：

 cA = condenseM(A,m)
 cA = 

 3     1     6
 4     0     2
 0     5     0
 1     4     1
 2     0     5
 0     3     0

Answer 1

这是使用cellfun进行矢量化的可能代码，但在我的机器上它比你循环慢：

<ItemGroup>
<Reference Include="System.Management.Automation" />
</ItemGroup>

矢量化特定的matlab代码

1 个答案: