How can I select the aerosol values from different size of matrix?

here, I have 3 different size of matrix:

First case; 2X2 matrix which look like [0,0.550;0,0.1293], second case is 1X2 matrix - [0.550,0], and third case is 4X2 matrix - [0.4430,1.1936;0.5550,1;0.670,0.8422;0.8650,0.6459]

Here I want select aerosol which are bolded in above matrix and i have written code but its not working. I am trying to plot my TOA variable with Aerosol but i have different size of matrix and having problem to select specfic aerosol value? So, can you guys give some ideas?

A = size([0 0; 1 1]);%just assigning 2X2 matrix for comparison


for dates = 1:115
       
    for band = 1%[1 2 3 4 5 7]
            SM_p029r029(dates).TOA = mean(SM_BQA(dates).SREF(band).TOA_Ref);
            if size(Out(dates).aerosol)>=size(A)
                SM_p029r029(dates).Aerosol1 = Out(dates).aerosol(2,2);
%                 figure(band)
%                 scatter(Aerosol1,SM_TOA,50,'MarkerEdgeColor','r','MarkerFaceColor','r','LineWidth',2);
%                 hold on
            else
                SM_p029r029(dates).Aerosol1 = Out(dates).aerosol(1,2);
%                 scatter(Aerosol1,SM_TOA,50,'MarkerEdgeColor','r','MarkerFaceColor','r','LineWidth',2);
            end
 
    end
end
save('Aerosol_TOA','SM_p029r029', '-v7.3');

Answer 1

[Voss]

Note that A is [2 2]

A = size([0 0; 1 1])

A = 1×2

2 2

so size(A) is [1 2]

size(A)

ans = 1×2

1 2

So when you compare size(Out(dates).aerosol) with size(A) here:

if size(Out(dates).aerosol)>=size(A)

you are checking size(Out(dates).aerosol) >= [1 2], and since size(Out(dates).aerosol) can be [1 2], [2 2] or [4 2], that comparison is always [true true]

size([0 0]) >= size(A)

ans = 1×2 logical array
   1   1

size([0 0; 0 0]) >= size(A)

ans = 1×2 logical array
   1   1

size([0 0; 0 0; 0 0; 0 0]) >= size(A)

ans = 1×2 logical array
   1   1

so the code inside the if block is always executed, and element (2,2) of Out(dates).aerosol is always (attempted to be) retrieved

SM_p029r029(dates).Aerosol1 = Out(dates).aerosol(2,2)

but in case size(Out(dates).aerosol) is [1 2], that's an error because element (2,2) doesn't exist.

What you really mean to be doing is, instead of comparing to size(A), compare to A, since A is [2 2]

size([0 0]) >= A

ans = 1×2 logical array
   0   1

size([0 0; 0 0]) >= A

ans = 1×2 logical array
   1   1

size([0 0; 0 0; 0 0; 0 0]) >= A

ans = 1×2 logical array
   1   1

That way, the else block will be executed when size(Out(dates).aerosol) is [1 2]. (A vector if condition is considered true only if all elements of the condition are true.)

However, you can do away with the if/else entirely and just do:

SM_p029r029(dates).Aerosol1 = Out(dates).aerosol(min(size(Out(dates).aerosol,1),2),2)

because the expression min(size(Out(dates).aerosol,1),2) gives you either the index of the last row of Out(dates).aerosol or 2, whichever is smaller, which is exactly what you need

min(size([0 0],1),2)

ans = 1

min(size([0 0; 0 0],1),2)

ans = 2

min(size([0 0; 0 0; 0 0; 0 0],1),2)

ans = 2

Or more succinctly:

SM_p029r029(dates).Aerosol1 = Out(dates).aerosol(min(end,2),2);

[Rahul Shah]

Thank you for comment and I already solved this problem last week.

[Voss]

You're welcome! Thanks for letting me know!