Extract matrix subset based on latitude and longitude

I have a matrix of data and want to extract various subsets (0.5 degree grids) based on latitude and longitude. My file is not one that I downloaded from NASA, ect...

I have been trying to use "find" where latitude and longitude are columns 1 & 2 of the matrix "all_time":

x=all_time(:,3:15);% tem=find(all_time(:,1)<27.5 & all_time(:,1)>28.0 & all_time(:,2)<-79 & all_time(:,2)>-78.5); box1=x(tem);

I am trying to extract boxes of 0.5 by 0.5 degrees for all the variables in columns 3 to 15 of the matrix. My box1 is an empty matrix.

Thanks

Answer 1

[Kirby Fears]

Janet,

These conditions are contradictory:

all_time(:,1)<27.5 & all_time(:,1)>28.0

None of your values could be below 27.5 and above 28 at the same time. I suppose you meant to flip those comparators as:

all_time(:,1)>27.5 & all_time(:,1)<28.0

Also, tem will contain the rows satisfying your longitude and latitude conditions. If you'd like to extract all columns of x corresponding to those rows, you'd index like this:

box1=x(tem,:);

Hope this helps.

[Janet Reimer]

Yes, thank you, I had inadvertently flipped the signs, but "box1" is still empty.

[Kirby Fears]

Are you sure you have data in that matrix meeting all conditions? You can try removing one condition at a time to see which one is causing a problem. You might need to use a >= or <= sign.