find the nearest value

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crispin Donnelly
crispin Donnelly 2013-8-22
评论： Walter Roberson 2016-5-9
Hi!
Can someone help with this problem please.....
if for example, q = [1 3 6 8 10 15]
find(q==8) returns ans = 4
find(q==9) returns Empty matrix: 1-by-0 because there is no value 9
...how do I query, find the value in q that is nearest to 9??

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采纳的回答

Iain
Iain 2013-8-22
q = [1 3 6 8 10 15];
v = 9;
[~,ans] = (min(abs(q - v)))

更多回答（1 个）

mohamed azuan wahari
编辑：Walter Roberson 2016-5-9
find nearest value on matrix
Can someone help with this problem please.....
for example
a= 1250
matrix_b=[98 125 945 1005;
105 204 1105 1249;
200 250 1299 1450;
300 450 1350 1850]
want to find nearest equal or greater than a=1250
and the answer should be 1299
  2 个评论
Walter Roberson
Walter Roberson 2016-5-9
v = sort(matrix_b(:));
vidx = floor(interp1(v, 1:length(v), a, 'linear', 'extrap'));
if vidx ~= 0
result = b(vidx);
end
Or
v = sort(matrix_b(:));
vidx = find(v >= a, 1, 'first');
if ~isempty(vidx)
result = v(vidx);
end
or
v = sort(matrix_b(:));
[~, vidx] = histc(a, v);
if vidx ~= 0
result = v(vidx);
end
The middle of these is probably the easiest to think about, but it cannot be generalized to a list of a values like the other ones can (aside from the testing to be sure that a result was found.)
Walter Roberson
Walter Roberson 2016-5-9
If you have R2016a or later, then
v = sort(matrix_b(:));
result = interp1(v, v, a, 'previous');

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