User defined distance function

Question

MByk 2017-7-2

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/347110-user-defined-distance-function

评论： MByk 2017-7-2

I'am trying to calculate Canberra distance (formula of the Canberra distance sum(a-b/|a|+|b|)) by defining a custom distance function but it is not working correctly. Would you help correcting my function? Thank you.

 r = [0 3 4 5;7 6 3 -1;-1 1 -1 1;2 3 4 5];
 dist = squareform(pdist(r,@f)) 
 function dC = f(a,b)
   [m,~]=size(b);
   for i=1:m
      dC = sum(abs(a - b(i,:))./(abs(a) + abs(b(i,:))));
   end
 end

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Answer 1

Andrei Bobrov 2017-7-2

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/347110-user-defined-distance-function#answer_272689

编辑：Andrei Bobrov 2017-7-2

在 MATLAB Online 中打开

r = [0 3 4 5;7 6 3 -1;-1 1 -1 1;2 3 4 5];

for MATLAB >= R2016b

dist = squareform(pdist(r,@(a,b)sum(abs(a - b)./(abs(a) + abs(b)),2)))

for MATLAB <= R2016a

f = @(a,b)sum(abs(bsxfun(@minus,a,b))./bsxfun(@plus,abs(a),abs(b)),2);
dist1 = squareform(pdist(r,f))

for your code

dist = squareform(pdist(r,@f))
function dC = f2(a,b)
    [m,~] = size(b);
    dC = zeros(m,1);
    for ii=1:m
        dC(ii) = sum(abs(a - b(ii,:))./(abs(a) + abs(b(ii,:))));
    end
end