MATLAB: How to get a new cell array containing the repeated elements in an original cell

Question

For example if I have an original cell as

celloriginal={'apple','bird','cat','bird','zoo','bird','cat'};

and I want to obtain a new cell which contains the elements, 'bird' and 'cat', that appear multiple times in the original cell

cellnew={'bird','cat'}

I have tried unique(celloriginal), but got no clue what to do next. Help would be really appreciated.

Answer 1

[g,val] = findgroups(celloriginal);
out = val(histcounts(g,1:max(g)+1)>1);

or

[a,~,c] = unique(celloriginal);
out = a(accumarray(c,1)>1);