How do i insert one value from one array to another array

Question

Lars Urban 2022-8-2

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评论： Lars Urban 2022-8-3

I have 2 arrays with coordinates. For example

A = [1,2;2,1;1,1;1,3;3,2] 
A = 5×2
     1     2
     2     1
     1     1
     1     3
     3     2
B = [0.5,0.5;2,2]
B = 2×2
    0.5000    0.5000
    2.0000    2.0000

I compute for every point in A the nearest Point from B. I use dsearchn

k = dsearchn(B,A)
k = 5×1
     2
     2
     1
     2
     2

Now I want to give every point in B the next points from A. Making for every point in B a list of nearest points from A. Like point B(2,:) ans = 2 , 2 has the next points A(1,:),A(2,:),A(4,:) and A(5,:). I have no clue how to do it right and efficient.

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Rik 2022-8-2

What is the actual output in terms of Matlab variables you want?

Lars Urban 2022-8-2

I thought about a structure array where it is divided by coordinate of B in x and y and the a list of double from A.x and A.y

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Answer 1

Bruno Luong 2022-8-2

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https://ww2.mathworks.cn/matlabcentral/answers/1772870-how-do-i-insert-one-value-from-one-array-to-another-array#answer_1020060

在 MATLAB Online 中打开

See if s is what you want or not (not clear for me)

A = [1,2;2,1;1,1;1,3;3,2] 
A = 5×2
     1     2
     2     1
     1     1
     1     3
     3     2
B = [0.5,0.5;2,2]
B = 2×2
    0.5000    0.5000
    2.0000    2.0000
k = dsearchn(B,A)
k = 5×1
     2
     2
     1
     2
     2
AA = accumarray(k, (1:size(A,1))', [], @(r) {A(r,:)});
s = struct('B', num2cell(B,2), 'A', AA)
s = 2×1 struct array with fields:
    B
    A
s(1).B
ans = 1×2
    0.5000    0.5000
s(1).A
ans = 1×2
     1     1
s(2).B
ans = 1×2
     2     2
s(2).A
ans = 4×2
     1     2
     2     1
     1     3
     3     2

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Lars Urban 2022-8-3

Yes this is what i want at the end. Sorry for the bad description of my problem. Thank you!

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Answer 2

David Hill 2022-8-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1772870-how-do-i-insert-one-value-from-one-array-to-another-array#answer_1020020

在 MATLAB Online 中打开

Look at pdist2

A = [1,2;2,1;1,1;1,3;3,2] ;
B = [0.5,0.5;2,2];
pdist2(A,B)
ans = 5×2
    1.5811    1.0000
    1.5811    1.0000
    0.7071    1.4142
    2.5495    1.4142
    2.9155    1.0000

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Lars Urban 2022-8-2

It would be end in the same problem where i have to sort each point with the closest distance to one point B. I have found w dsearch for each point in A the closest point in B but i want to sum for every point in B their closest points from A.

David Hill 2022-8-2

I don't understand your comment. Each column above gives the distance between each point in B with all the points in A. You could sort each column and then index into A to provide the sorted listing of the closest points of A to each point in B.

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