Vectorizing a loop calculation

3 次查看（过去 30 天）

显示更早的评论

Azura Hashim 2018-2-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/384540-vectorizing-a-loop-calculation

评论： Meade 2018-2-26

在 MATLAB Online 中打开

Hi,

Is it possible to convert the loop below into a vector calculation? Thank you.

dataset=table();
dataset.value=rand(30,1);
dataset.time=sort(rand(30,1));
timefilter=dataset.time-0.2;
result1=repmat(NaN,height(dataset),1);
result2=repmat(NaN,height(dataset),1);
result3=repmat(NaN,height(dataset),1);
%Loop:
for row=5:height(dataset)
startrow=min(find(dataset.time >=timefilter(row)));
result1(row,1)=nansum(dataset.value(startrow:row));
result2(row,1)=length(dataset.value(startrow:row));
result3(row,1)=nanstd(dataset.value(startrow:row)) ;
end

3 个评论
显示 1更早的评论隐藏 1更早的评论

Azura Hashim 2018-2-26

Thanks. Yes nansum and nanstd is not required here. I took it from the code that handles the full size data which has NaNs.

Meade 2018-2-26

The sum, length, and std calculations are so trivially fast that it might be fastest to calculate them for the entire array, then just sort. If this doesn't seem unreasonable for your use, I would use bsxfun or arrayfun on your data, then sort. That would be fastest I think.

That would get rid of the loop entirely.

请先登录，再进行评论。

请先登录，再回答此问题。