distance between array entries

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amateurintraining
amateurintraining 2017-11-29
评论： Andrei Bobrov 2017-11-29
How do you write code to get which of the entries stored in an array it is closest to for each data point?
For example:
array: [4 9 7 3 10 19 2 11]
and you want to find which entry each entry is closest to. So, in the above array, the answer would be:
[4 5 2 1 2 8 4 5]
(the number 4 is closest in value to the 4th entry in the array...the number 9 is closest in value to the 5th entry in the array...etc.)
  1 个评论
Jos (10584)
Jos (10584) 2017-11-29
You should define " closest" more accurately! Why is 9 closer to 10 rather than 11? And I would argue that any number is closest to itself, so 1:8 would be my answer ;)

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回答（3 个）

KSSV
KSSV 2017-11-29
编辑：KSSV 2017-11-29
Read about knnsearch.
A = [4 9 7 3 10 19 2 11] ;
B = [4 5 2 1 2 8 4 5] ;
idx = knnsearch(A',A','k',2) ;
iwant = idx(:,2)
Andrei Bobrov
Andrei Bobrov 2017-11-29
a = [4 9 7 3 10 19 2 11];
[~,iout] = min(abs(a(:)-a(:)')+diag(nan(numel(a),1)),[],2);
Roger Stafford
Roger Stafford 2017-11-29
Let 'a' be your array (row vector.)
n = size(a,2);
[t,p] = sort(a);
q = 1:n; q(p) = q;
t = diff(t);
t = [inf,t;t,inf];
[~,r] = min(t);
r = (1:n)+2*r-3;
p = p(r(q)); % p is the desired result

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