Replace each element of a matrix with the number it is closest to in a set of discrete values without using for loop

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Ted
Ted 2017-8-18
编辑： Andrei Bobrov 2017-8-19
I have a set of discrete values in the row vector <list>. I want to take a vector M of real doubles, and for each element M(j) in M I want to replace M(j) with the element in <list> that is closest to M(i) on the number line. For example, if my list was [2 4] and my matrix was [1.1, 3.2, 5, -17], the resulting matrix would be [2, 4, 4, 2].
I know I can do this with a for loop:
for j=1:length(M)
[m mn]=min(abs(list-M(j)));
M(j)=list(mn);
end
Is there any way to do this without a for loop?

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采纳的回答

Andrei Bobrov
Andrei Bobrov 2017-8-18
编辑：Andrei Bobrov 2017-8-19
A = [2 4], B = [1.1, 3.2, 5, -17]
[~, ii] = min(abs(bsxfun(@minus,B(:),A(:).')),[],2); % MATLAB <= R2016a
[~, ii] = min(abs(B(:) - A(:).'),[],2); % MATLAB >= R2016b
out = A(ii)
or
F = griddedInterpolant(A,'nearest');
out = F(B)
or
out = interp1(A,B,'nearest','extrap');

更多回答（1 个）

MG Poirot
MG Poirot 2017-8-18
编辑：MG Poirot 2017-8-18
I think I've got a simple solution for you by finding the minimal difference after matrix subtraction:
list = [2 4]';
M = [1.1 3.2 5 -17];
A = repmat(M,numel(list),1)
B = repmat(list,1,numel(M))
dif = abs(A-B)
[~, I] = min(dif,[],1)
list(I)'
-mgp

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