Avoid loops with mapping toolbox "setltln"
显示 更早的评论
Hi all, I'm looking for a clever way to optimize the following chunk of code. The function is to get a grid of lat, lon coordinates using the reference matrix R, and the indices of Z.
However, with such huge dimensions, this nested for loop is painfully slow! How can I avoid for loops in this case?
[Z, R] = arcgridread('biloxi_ms.asc');
tempLAT=zeros(9721,10801);
tempLON=zeros(9721,10801);
for i =1:9721
for j = 1:10801
[tempLAT(i,j), tempLON(i,j)] = setltln(Z, R, i, j);
end
end
Best, Rob
采纳的回答
Sean de Wolski
2015-8-4
You could build a grid and call setltln on all of it. This will consume a bit more memory since you'll need to store ii, jj. A hybrid approach might be to run a loop over smaller meshgrids.
[ii, jj] = meshgrid(1:9271,1:10801)
[tempLAT, tempLON]= setltln(Z, R, ii, ij);
Also, parallel computing could help here if you have the parallel computing toolbox. Simply, turn the outer loop into a parfor.
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 
