finding distance within a range of distance

Question

Mohammad Golam Kibria 2011-5-23

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/8006-finding-distance-within-a-range-of-distance

[EDIT: 20110524 01:36 CDT - reformat, clarify - WDR]

Hi I have a matrix as follows.

I =
       1     1     5     1     1     1     8
       1     1     1     1     1     1     1
       1     1     1     1     1     1     1
       1     1     5     2     1     1     1
       1     1     1     1     1     5     1
       1     1     1     1     1     1     1

I need to know whether distances of value 5 with another 5 are in the range 3. Thanks in advance

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Answer 1

Andrei Bobrov 2011-5-24

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https://ww2.mathworks.cn/matlabcentral/answers/8006-finding-distance-within-a-range-of-distance#answer_11111

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ij5 = find(I==5);
[i5 j5] = ind2sub(size(I),ij5);
out1 = [nchoosek(ij5,2) bsxfun(@(x,y)sqrt(diff(nchoosek(x,2),[],2).^2....
                                       +diff(nchoosek(y,2),[],2).^2),i5,j5)];
[non,indout]=min(out1(:,3)); 
out = out1(indout,:);

in vector "out" the first Two members - the indices of matrix "I", the third distance between them

EDIT

out = out1(out1(:,3) <= 3,:)

EDIT EDIT

The answer to the last Mohammad comment:

[ii,jj]=ind2sub(size(I),nchoosek(find(I==5),2));
out1 = [ii jj sqrt(sum(reshape(diff([ii;jj],[],2).^2,[],2),2))];
[non,indout]=min(out1(:,5)); % 1 variant
out = out1(indout,:);
out = out1(out1(:,5) <= 3,:); % 2 variant

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Mohammad Golam Kibria 2011-5-25

your answer is correct.but I need indices in 2D form i.e. in the form as follows:

1 3 4 3 3 the first two is the row and column of first 5

second two is the row and column of second 5 and last one is the distance. or any other convenient way to get the indices in 2D form with distance

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Answer 2

Wolfgang Schwanghart 2011-5-23

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https://ww2.mathworks.cn/matlabcentral/answers/8006-finding-distance-within-a-range-of-distance#answer_11003

在 MATLAB Online 中打开

How about

[X,Y] = meshgrid(1:size(I,2),1:size(I,1));
ix = find(I == 5);
d = hypot(bsxfun(@minus,X(ix),X(ix)'),bsxfun(@minus,Y(ix),Y(ix)'));
[ixd,cc] = find(d<=3 & d>0);
II = false(size(I));
II(ix(ixd)) = true;

Cheers, W.