CODEWITHSUNDEEP
matlaboptimizationcoordinates
user2618054
user2618054

Reputation: 15

How to find nearest points from two different sized sets with Matlab?

I have two sets each containing x,y coordinates for a series of points and codes respectively.

Considering the huge sizes of files I'm looking for an optimized way in Matlab to connect each point from the first set with the point from the second set that is the nearest based on Eucledian distance calculated with the help of coordinates values.

    X        Y

A=[155413 4564566; 156464 456585; ... ; n]


   code   X       Y
B=[1001 155413 4564566; 1015 156464 456585; ... ; m]

The tricky part is they are of different length. For each point (line from A) I need the corresponding "code" variable from B as being found as the closest.

Thanks.

Upvotes: 1

Views: 881

Answers (1)

Luis Mendo
Luis Mendo

Reputation: 112659

Since there are two coordinates, an approach based on complex numbers can be used, which results in a very easy solution:

A = [1 2; 3 4; 5 6; 7 8; 9 10]; % GPS points
B = [1001 0 0; 1002 7 7]; % postcode points

A_compl = A(:,1) + j*A(:,2); % transform to complex
B_compl = B(:,2) + j*B(:,3);
[AA BB] = meshgrid(A_compl, B_compl); % generate all combinations
distance = abs(AA-BB); % Euclicean distance in R^2 is modulus in C
[min_distance min_index] = min(distance);
code = B(min_index,1) % solution

This requires two complex arrays, AAand BB, of size numA times numB, where numA and numB denote the number of A and B points. If they are too large for your computer's memory you'll need a for loop to divide A into chunks of an acceptable size.

Upvotes: 1

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