Make Matlab search for the closest match to a given pattern within a matrix?

If I have a data set of something that occurred during a day, for example stored in a 550x1 variable. Could I use it as a target data set to search through a much bigger matrix containing the same type of values but during an entire year, for example a 550x365 matrix and have Matlab tell me where the closest matching (with the same length) pattern occurred? Is there a function for that?

Note that I’m not looking for an exact match, what I’m looking for might not even be even close to a 100% match. But can Matlab identify what would be classified as the closest match? And perhaps even give me some sort of confidence value of how good the match was?

Answer 1

[Star Strider]

If you have the Statistics Toolbox, use the knnsearch function. If you don’t have it, the same algorithm is fairly easy to implement:

M = randi(10, 20, 5);               % Search Matrix
T = randi(10,  1, 5);               % Search Vector

for k1 = 1:size(M,1)
    D(k1) = sqrt(sum((M(k1,:) - T).^2));
end

The index of the lowest value of ‘D’ is the index of the row in ‘M’ that is the closest match to ‘T’.