how to reduce the use of repeated for loops as i explained below???

Question

M.Prasanna kumar 2019-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/477166-how-to-reduce-the-use-of-repeated-for-loops-as-i-explained-below

评论： M.Prasanna kumar 2019-8-23

采纳的回答： Rik

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when SS =1 , KK loop should not take the value from 1 to 3

when SS = 2:23 , KK loop should not run for SS-1:SS+1

when SS =24 , KK loop should not take the value from 22 to 24

to calculate the variable "dist" i used three sets of for loops. is it possible to reduce

I am able to get the answer but i dont want to repeat the same code for three times. how to resolve the problem???

for ss = 1
    for kk = setdiff(1:no_receivers+1,1:3)
        for ii = 1:no_gridsx
            dist(ii,1:250,kk,ss) = sqrt((apert_x(1,ss)-X(ii,1:250)).^2+(apert_y(1,ss)-Y(ii,1:250)).^2)+sqrt((X(ii,1:250)-apert_x(1,kk)).^2+(Y(ii,1:250)-apert_y(1,kk)).^2);
        end
    end
end
for ss = 2:23
    for kk = setdiff(1:no_receivers+1,ss-1:ss+1)
        for ii = 1:no_gridsx
            dist(ii,1:250,kk,ss) = sqrt((apert_x(1,ss)-X(ii,1:250)).^2+(apert_y(1,ss)-Y(ii,1:250)).^2)+sqrt((X(ii,1:250)-apert_x(1,kk)).^2+(Y(ii,1:250)-apert_y(1,kk)).^2);
        end
    end
end
for ss = 24
    for kk = setdiff(1:no_receivers+1,22:24)
        for ii = 1:no_gridsx
            dist(ii,1:250,kk,ss) = sqrt((apert_x(1,ss)-X(ii,1:250)).^2+(apert_y(1,ss)-Y(ii,1:250)).^2)+sqrt((X(ii,1:250)-apert_x(1,kk)).^2+(Y(ii,1:250)-apert_y(1,kk)).^2);
        end
    end
end

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Image Analyst 2019-8-22

I rescued this from the spam quarantine.

M.Prasanna kumar 2019-8-22

thank you image analyst

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Answer 1

Rik 2019-8-22

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https://ww2.mathworks.cn/matlabcentral/answers/477166-how-to-reduce-the-use-of-repeated-for-loops-as-i-explained-below#answer_388635

在 MATLAB Online 中打开

Use a temporary variable to adapt your range. The code below show one such approach.

%intitialize for testing
no_gridsx=10;
no_receivers=26;
ss_max=24;
dist=NaN(no_gridsx,250,no_receivers+1,ss_max);
for ss = 1:ss_max
    skips=ss-1:ss+1;
    if ss==1%correct for edge cases
        skips=skips+1;
    elseif ss==ss_max
        skips=skips-1;
    end
    for kk = setdiff(1:no_receivers+1,skips)
        for ii = 1:no_gridsx
            dist(ii,1:250,kk,ss) = ...
                sqrt((apert_x(1,ss)-X(ii,1:250)).^2+(apert_y(1,ss)-Y(ii,1:250)).^2) ...
                +sqrt((X(ii,1:250)-apert_x(1,kk)).^2+(Y(ii,1:250)-apert_y(1,kk)).^2);
        end
    end
end

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Stephen23 2019-8-23

编辑：Stephen23 2019-8-23

在 MATLAB Online 中打开

"why did you subtract ss==24 & add ss==1 , what is the logic behind this"

(ss-1:ss+1)-(ss==24)+(ss==1)
%^^^^^^^^^^                  creates a vector, exactly like you did
%          ^^^^^^^^^         when ss==24 subtracts 1 from the vector
%                   ^^^^^^^^ when ss==1 adds 1 to the vector

With setdiff this provides exactly the vectors described on the first three lines of your question.

M.Prasanna kumar 2019-8-23