finding the closest grid

I have 2 variables and each of 3 discretization say for example, first variable have values (2,4,6) and second variable have (1,3,5). so out of these I can make a 9 combination which looks something like this: grid = {(2,1), (2,3), (2,5), (4,1), (4,3), (4,5), (6,1), (6,3), (6,5)}

Suppose if I have a combination (2.8, 4.2) and I would like to find the closest value out of my 9 combination for it

How can I do that ?

Thanks

Answer 1

[Walter Roberson]

nearestx = interp1([2,4,6], [2,4,6], comb(:,1), 'nearest');
nearesty = interp1([1,3,5], [1,3,5], comb(:,2), 'nearest');

There are other ways as well.

[Matt Learner]

Please can you let me know what are the other ways. Cos, I have around 64 combinations obtained from 2 variables and I have to select the nearest combination (out of 64) for the given combination

[Walter Roberson]

The above will handle that situation as well.

var1vals = sort([2, 4, 6, 7, -3, 11, pi^2, sqrt(30)]);

var2vals = sort([1, 3, 5, 9, 1.15, 33, -5, -8]);

nearestx = interp1(var1vals, var1vals, comb(:,1), 'nearest');

nearesty = interp1(var2vals, var2vals, comb(:,2), 'nearest');

An alternative:

var1vals = sort([2, 4, 6, 7, -3, 11, pi^2, sqrt(30)]);

var2vals = sort([1, 3, 5, 9, 1.15, 33, -5, -8]);

[mindiffx, minidxx] = min(bsxfun(@(a,b) abs(a-b), comb(:,1), var1vals), [], 2);

[mindiffy, minidxy] = min(bsxfun(@(a,b) abs(a-b), comb(:,2), var2vals), [], 2);

nearestx = var1vals(minidxx);

nearesty = var2vals(minidxy);

Note that both of these approaches handle all of the combinations at the same time, if the combinations are stored in the matrix "comb" with the first column being the first variable and the second column being the second variable.