Most common pair in a matrix.

I have a list of lat/lon coordinates and I would like to find the most common locations. Is there a built in function for this?

Thank you.

Answer 1

[Star Strider]

Try this:

M = randi(5, 25, 2);                                                            % Create ‘LatLon’ Data
[Mu,~,idx] = unique(M, 'rows');                                                 % Unique Rows
Tally = accumarray(idx, (1:numel(idx)).', [], @(x) {M(x,:)});                   % Calculate Frequencies, Return Pairs By Group
pairs = cellfun(@(x)size(x,1), Tally);                                          % Recover ‘LatLon’ Pairs
[~,ixs] = sort(pairs, 'descend');                                               % Sort Them
Result = table(Mu(ixs,:),pairs(ixs), 'VariableNames',{'LatLon','Frequency'});   % Output Table Of Pairs & Frequencies

I did my best to comment-document it. Use your own latitude & longitude coordinates for ‘M’. It may be necessary to use uniquetol with the 'ByRows' option if the coordinates are not exactly the same.

[Erick Koenig]

Awesome! works perfectly. That's exactly what I was looking to do. Thank you.

[Star Strider]

Thank you! As always, my pleasure!