Distance Between a Set of Points

Question

Suyapa Gonzalez 2015-6-18

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https://ww2.mathworks.cn/matlabcentral/answers/224427-distance-between-a-set-of-points

评论： Walter Roberson 2018-11-17

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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Answer 1

Joseph Cheng 2015-6-18

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https://ww2.mathworks.cn/matlabcentral/answers/224427-distance-between-a-set-of-points#answer_183192

编辑：Joseph Cheng 2015-6-18

在 MATLAB Online 中打开

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));

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Suyapa Gonzalez 2015-6-18

Where do I plug in my data points? I have 15 different pair of coordinates.

Joseph Cheng 2015-6-18

it would be the xy points, since i do not have your data i created my own list of X and Y values.

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Answer 2

Jacob Strang 2018-11-17

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https://ww2.mathworks.cn/matlabcentral/answers/224427-distance-between-a-set-of-points#answer_347547

在 MATLAB Online 中打开

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.