清空筛选条件
清空筛选条件

Avoid loops with mapping toolbox "setltln"

2 次查看（过去 30 天）
Robert Jenkins
Robert Jenkins 2015-8-4
回答： Sean de Wolski 2015-8-4
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

请先登录，再回答此问题。

采纳的回答

Sean de Wolski
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 Help Center 和 File Exchange 中查找有关 Execution Speed 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by