I have a region with about 144 points. What i want to achieve is to measure the distance of a point with all others and store it in an array. I want to do this for all the points. If possible i would like to store this data in such a manner that there in no repetition. And i should be able to make queries like- All the distances between all the points without repetition, sum of all the distances for point no56 etc.
I have a 3*144 array with two columns storing the coordinates of the points.
A possible solution (I am not really clear with what you mean by no repetition, though):
X are your points with coordinates x = X(:,1), y = X(:,2)
dist = sqrt(bsxfun(@minus,X(:,1),X(:,1)').^2 + bsxfun(@minus,X(:,2),X(:,2)').^2)
so
dist(i,j) is the euclidean distance between i and j
of course the matrix is symmetric. You can easily reduce the complexity involved.
Let's say your array is A, where each column stores the coordinates of a single point. To obtain the combinations of all point pairs (without repetitions), use nchoosek:
pairs = nchoosek(1:size(A, 2), 2)
Then calculate the Euclidean distance like so:
dist = sqrt(sum((A(:, pairs(:, 1)) - A(:, pairs(:, 2))) .^ 2, 1))
If you have the Statistics Toolbox installed, you can use pdist(A) instead for the same effect.
If you have the statistics toolbox, and if you have all your data in the array X, then
D = pdist(X)
gives all the pairwise distances between all points in X.
来源：https://stackoverflow.com/questions/14483468/calculating-distance-of-all-the-points-in-a-region-with-each-other