Storing and passing all iterations to an array outside the nested for loops

Question

Banjo 2019-12-23

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编辑： Banjo 2019-12-23

Hello, my problem is basically that I don't know how to store and pass all 8736 different values from L(k) to the outside of nested for loops in a form of an array (8736x1), so I can use it for further processing and comparing with some other arrays in my code. Code is below...

    Lw =[52x1]; Ld=[7x1]; Lh=[24x6]; Ly=number;
    for i=1:length(Lw)
        for j=1:length(Ld)
            for k=1:length(Lh)
                if ((i>=1 && i<=8)||(i>=44 && i<=52))
                    if (j>=1 && j<=5)
                        L(k)=Lw(i)*Ld(j)*Lh(k,1)*Ly;
                    else
                        L(k)=Lw(i)*Ld(j)*Lh(k,2)*Ly;
                    end  
                end
                if (i>=18 && i<=30)
                    if (j>=1 && j<=5)
                        L(k)=Lw(i)*Ld(j)*Lh(k,3)*Ly;
                    else
                        L(k)=Lw(i)*Ld(j)*Lh(k,4)*Ly;
                    end
                end
                if (i>=9 && i<=17)||(i>=31 && i<=43)
                    if (j>=1 && j<=5)
                        L(k)=Lw(i)*Ld(j)*Lh(k,5)*Ly;
                    else
                        L(k)=Lw(i)*Ld(j)*Lh(k,6)*Ly;
                    end
                end
                L(k)
            end
        end
    end
    L to be passed here with all 8736 values

Thank you in advance.

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Answer 1

per isakson 2019-12-23

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编辑：per isakson 2019-12-23

在 MATLAB Online 中打开

Read Multidimensional Arrays carefully and then try (which implements the advise of Image Analyst)

>> clearvars
>> cssm
>> sum(double(isnan(L(:))))
ans =
     0
>> numel(L)
ans =
        8736
>> 

where the script, cssm, is your script with a few modifications

%% cssm
Lw = rand(52,1); Ld=rand(7,1); Lh=rand(24,6); Ly = 17;
L = nan( length(Lw), length(Ld), length(Lh) );  % pre-allocate
for ii=1:length(Lw)
    for jj=1:length(Ld)
        for kk=1:length(Lh) % size(Lh,1) (if that's what you intend) is better
            if ((ii>=1 && ii<=8)||(ii>=44 && ii<=52))
                if (jj>=1 && jj<=5)
                    L(ii,jj,kk)=Lw(ii)*Ld(jj)*Lh(kk,1)*Ly;
                else
                    L(ii,jj,kk)=Lw(ii)*Ld(jj)*Lh(kk,2)*Ly;
                end
            end
            if (ii>=18 && ii<=30)
                if (jj>=1 && jj<=5)
                    L(ii,jj,kk)=Lw(ii)*Ld(jj)*Lh(kk,3)*Ly;
                else
                    L(ii,jj,kk)=Lw(ii)*Ld(jj)*Lh(kk,4)*Ly;
                end
            end
            if (ii>=9 && ii<=17)||(ii>=31 && ii<=43)
                if (jj>=1 && jj<=5)
                    L(ii,jj,kk)=Lw(ii)*Ld(jj)*Lh(kk,5)*Ly;
                else
                    L(ii,jj,kk)=Lw(ii)*Ld(jj)*Lh(kk,6)*Ly;
                end
            end
        end
    end
end

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Image Analyst 2019-12-23

Banjo, also take note of the nice change he made to change the variable names from i to ii and j to jj because i and j also function as the imaginary variable in MATLAB so we recommend to NOT use i and j as variable names.

Banjo 2019-12-23

编辑：Banjo 2019-12-23

Thank you both!! I also used reshape at the end, but anyhow I made it to work.

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Answer 2

Image Analyst 2019-12-23

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编辑：Image Analyst 2019-12-23

L is available after all the loops terminate. It does not exist solely inside the loop and then vanish when the loops end. Simply pass L to your other code for further processing.

If you don't want to overwrite L on the inner loop, simply add additional indexes L(i, j, k).