How to vectorize this code to eliminate nested For loops
显示 更早的评论
Would like to know how this code be vectorized:
for y=1:rows
for x=1:cols
if (segMat(y,x) == 255)
Energy(y,x) = Energy(y,x) + motionMap(y,x);
end
end
for y=1:rows
for x=1:cols
delta(y,x) = kronDel(255, segMat(y,x));
end
end
The kronDel function acts like the Kronecker delta.
2 个评论
Rik
2018-9-4
Is segMat a function or an array? The second set of loops could be replaced with a call to arrayfun, but this is not always a speed improvement.
Jae Min Lee
2018-9-4
编辑：Jae Min Lee
2018-9-4
采纳的回答
Walter Roberson
2018-9-4
编辑：Walter Roberson
2018-9-4
Assuming that motionMap is an array and not a function,
%no loop needed
mask = segMat == 255;
Energy(mask) = Energy(mask) + motionMap(mask);
After which you can have the second nested loop calling kronDel
kronDel looks more likely to be a function than an array, so it is difficult to know if we could vectorize that section.
I speculate that your kronDel function returns the first parameter if the second parameter is 0, and otherwise returns 0. If my speculation is correct, then the loops and call could be replaced by
delta = 255 .* (segMat == 0);
更多回答（0 个）
类别
在 帮助中心 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
