mg_getRowsWithKey.c​pp

For each unique id, it finds the rows with that id. Mex function.

If you have a large data matrix DATA and a vector of ids ID_VECTOR, you can do the following:
[unique_ids, map] = mg_getRowsWithKey(ID_VECTOR);
for(i =1:length(unique_ids)),
group_i_data = DATA(map{i},:);
//insert what you want to do on group_i_data here
end
ID_VECTOR can either be an n by 1 vector of real doubles or an n by 1 cell array of strings

compile with mex mg_getRowsWithKey.cpp