MATLAB: Getting rid of duplicate values in pairwise matrix to obtain single vector

distanceshistogramMATLABmatrix

Hello. I have a large (11000×11000) matrix of pairwise distances between 11000 points. I need to make a histogram of these distances. However, each vaue appears twice (e.g., in 2,2, 3,3 etc). How can I eliminate these duplicates to obtain a single vector of all unique values?

Thank you all so much.

Best Answer

The easiest is the pragmatic approach: get the counts with histcounts and divide that by 2.

X=randn(100,1);
[N,edges] = histcounts(X);
N=N/2;
centers=edges(2:end)-0.5*diff(edges(1:2));
bar(centers,N)

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MATLAB: How to count the number of times a number appear in a vector

Please try the following:

   A = [ 1 2 3 1 1 6 3 4 2 2 1 1 1 ];
   x = unique(A);
   N = numel(x);
   count = zeros(N,1);
   for k = 1:N
      count(k) = sum(A==x(k));
   end
   disp([ x(:) count ]);

HTH.

Rick

MATLAB: How to construct histogram with certain bin size

If you want strange bins, you'll have to do some work yourself (I changed the number generation btw). The labels are also not too difficult to generate.

Packages=randi([0 44000],200000,1);
edges=[0:1000:20000 inf];
labels=cell(numel(edges)-1,1);
labels{1}=sprintf('<%d',edges(2));
for n=2:(numel(labels)-1)
    labels{n}=sprintf('%d-%d',edges(n)+1,edges(n+1));
end
labels{end}=sprintf('>%d',edges(end-1));
[N,edges] = histcounts(Packages,edges);
centers=edges(1:(end-1))+diff(edges(1:2));
bar(centers,N)
xticks(centers)
set(gca,'XTickLabels',labels)
set(gca,'XTickLabelRotation',60)

Best Answer

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MATLAB: How to count the number of times a number appear in a vector

MATLAB: How to construct histogram with certain bin size

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