Distance Between a Set of Points
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I have a list of X and Y values and I need to get the distance between each point. So basically, the distance between point 1 to the other 14 points, point 2 to the other 14 points, point 3 to the other 14 points, for example. How do I do this without manually plotting in every pair of coordinates???
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Answers (3)
Joseph Cheng
on 18 Jun 2015
Edited: Joseph Cheng
on 18 Jun 2015
you can use the function nchoosek to generate the pairs:
xy= randi(10,15,2)
pairs = nchoosek(1:5,2)
p1 = xy(pairs(:,1),:);
p2 = xy(pairs(:,2),:);
distance = sqrt(sum((p1-p2).^2,2));
2 Comments
Joseph Cheng
on 18 Jun 2015
it would be the xy points, since i do not have your data i created my own list of X and Y values.
Jacob Strang
on 17 Nov 2018
I believe that pdist does this automatically if you provide more than 2 points, as seen in the first example on the linked page:
% Compute the Euclidean distance between pairs of observations, and convert the distance vector to a matrix using squareform.
% Create a matrix with three observations and two variables.
rng('default') % For reproducibility
X = rand(3,2);
% Compute the Euclidean distance.
D = pdist(X)
% D = 1×3
% 0.2954 1.0670 0.9448
% The pairwise distances are arranged in the order (2,1), (3,1), (3,2). You can easily locate the distance between observations i and j by using squareform.
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Walter Roberson
on 17 Nov 2018
You can use squareform() to convert the pdist() triangular matrix result to a symmetric square matrix.
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