Calculate distances between data points
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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
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Guillaume
2014-12-14
So do you want the distance between all of the points in one group and all of the points in another group, that is size(g1, 1) * size(g2, 1) distances, or something else?
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Guillaume
2014-12-14
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.
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matt dash
2014-12-15
Look on the file exchange for the file named "IPDM" http://www.mathworks.com/matlabcentral/fileexchange/18937-ipdm--inter-point-distance-matrix ... it does what you need and it is very fast:
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