MATLAB bsxfun或矢量化
MATLAB bsxfun或矢量化
提问于 2013-11-02 16:59:55
我一直致力于将代码向量化，主要是使用bsxfun，但我遇到了一个无法完全破解的场景。这是一个小问题的例子。我想删除这段代码中的for循环，但是我很难使用tempEA行。
Index = [2; 3; 4;];
dTime = [25; 26; 27; 28; 25; 26; 27; 28; 27; 28];
dIndex = [3; 3; 3; 2; 1; 3; 2; 4; 4; 2];
aTime = [30; 38; 34; 39; 30; 38; 34; 39; 34; 39];
aIndex = [4; 2; 5; 4; 5; 4; 4; 2; 2; 4];
EA = zeros(numel(Index));
for i = 1:numel(Index)
for j = 1:numel(Index)
tempEA = aTime(Index(i) == dIndex(:,1) & Index(j) == aIndex(:,1));
if i == j
elseif tempEA > 0
EA(i,j) = min(tempEA);
else
EA(i,j) = 50;
end
end
end答案应该是这样的：
EA =
0 50 34
38 0 30
34 50 0谢谢你提前帮忙。
回答 1
Stack Overflow用户
回答已采纳
发布于 2013-11-02 17:30:39
这使用bsxfun；没有循环。它假设在您的NaN值中没有aTime值。
N = numel(Index);
ii = bsxfun(@eq, dIndex.', Index); %'// selected values according to each i
jj = bsxfun(@eq, aIndex.', Index); %'// selected values according to each j
[ igrid jgrid ] = ndgrid(1:N); %// generate all combinations of i and j
match = double(ii(igrid(:),:) & jj(jgrid(:),:)); %// each row contains the matches for an (i,j) combination
match(~match) = NaN; %// these entries will not be considered when minimizing
result = min(bsxfun(@times, aTime, match.')); %'// minimize according to each row of "match"
result = reshape(result,[N N]);
result(isnan(result)) = 50; %// set NaN to 50
result(result<=0) = 50; %// set nonpositive values to 50
result(1:N+1:end) = 0; %// set diagonal to 0只有当您的result(result<=0) = 50;可以包含非正值时，行aTime才是必需的。可以吗？还是您的elseif tempEA > 0只是检查tempEA是否为空的一种方式？
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/19744447
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