MATLAB: How to retrieve the Key which belongs to a specified Value using the array Containers Map in MATLAB 7.7 (R2008b)

MATLAB

When I use the following code to retrieve the Key which belongs to a specified Value of a Containers Map array, I receive an error message:
Reproduction Steps
%%Create Containers Map
ticketMap = containers.Map(...
      {'jan', 'feb', 'march'}, ...
      {10, 20, 30});
% ticketMap = containers.Map( ...
%    {'Georgia', 'Alaska', 'Vermont', 'Oregon'}, ...
%    {'Atlanta', 'Juneau', 'Montpelier', 'Salem'})
%%Show keys
ticketMap.keys
keys(ticketMap)
%%Show values
ticketMap.values
values(ticketMap)
%%Retrieve specified value wrt defined key
testkey = 'feb';
msg_value = ticketMap.values({testkey})
% or

msg_value = values(ticketMap,{testkey})
%%Retrieve specified Key wrt defined Value, not possible...
testvalue = 30;
msg_key = ticketMap.values({testvalue})
% or
msg_key = values(ticketMap,{testvalue})
%%%BEGIN ERROR MESSAGE%%%
??? Error using ==> values
Specified key type does not match the type expected for this container.
%%%END ERROR MESSAGE%%%

Best Answer

To retrieve the Key which belongs to a specified Value of a Containers Map array the CELLFUN function can be used. An example is shown below:
%%Create Containers Map
ticketMap = containers.Map(...
      {'jan', 'feb', 'march'}, ...
      {10, 20, 30});
%%Retrieve specified Key wrt defined Value using CELLFUN
testvalue = 30;
testind = cellfun(@(x)isequal(x,testvalue),values(ticketMap));
testkeys = keys(ticketMap);
msg_key = testkeys(testind)
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