MATLAB: Calculate distances between data points

Question

Hi

I have 6 separated groups(as g1,g2,g3,…, g6) and each of them have some spatial data points as (x,y,z,k) where x,y,z determine position of each data point and k is its value, for example Temperature value at that point.

Note that the number of data points in each group is not equal.

I want to calculate distances between data points in each group and other data points in other groups.

Would you please guide me to solve my problem?

Thanks a lot.

Mani

Answer 1

Possibly, this is what you want:

g1 = randi([-100 100], 5, 4); %example data, a 5*4 matrix 
g2 = randi([-100 100], 3, 4); %example data, a 3*4 matrix
[idx1, idx2] = ndgrid(1:size(g1, 1), 1:size(g2, 1)); %row indices to calculate distance between
distance = arrayfun(@(row1, row2) norm(g2(row2, 1:3) - g1(row1, 1:3)), idx1, idx2)

Each row in the output matrix correspond to a row of g1, and each column to a row of g2. For example, the value at row 3, column 2 is the distance between row 3 of g1 and row 2 of g2.