问如何在Matlab中确定containers.Map中是否存在子键

EN

keySet =   {'1 2 4 5', '1 3 45', '1 2', '4 5'};
valueSet = [1, 2, 3, 4];
mapObj = containers.Map(keySet,valueSet)

% Get the Keys
key_list=keys(mapObj)
% Define the sub_key to be searched
sub_key='1 2'
% Split the sub_key in an cellarray of char
sub_key_c=strsplit(sub_key)
% Initialize counters
idx_f=0
n_of_match=0
cnt=0
found=[]
% Loop over the Container keys
for i=1:length(key_list)
   % Split the current key in an cellarray of char
   key_cell=strsplit(char(key_list(i)))
   % If the lenght of the searched sub_key is greater than the current
   % container key it can not a sub_key
   if(length(key_cell) < length(sub_key_c))
      continue
   end
   idx_f=0
   % Loop over the elements of the sub_key
   for j=1:length(sub_key_c)
      % Loop over the elements of the current key
      for k=1:length(key_cell)
         sub_key_c(j)
         key_cell(k)
         % If a match is found, increment the match counter and go to the
         % next sub_key element
         if(strcmp(sub_key_c(j),key_cell(k)))
            if(idx_f ~= k)
               n_of_match=n_of_match+1
               idx_f=k
               break
            end
         end
      end
   end
   % If the number of matches is equal to the length of the sub_key, the
   % sub_key is actually a sub_key
   if(n_of_match == length(sub_key_c))
      cnt=cnt+1;
      found(cnt)=i
      n_of_match=0
   end
   n_of_match=0
end
% Display the results
if(~isempty(found))
   disp(['The sub_key ' sub_key ' has been found in:'])
   for i=1:length(found)
      key_list(found(i))
   end
else
   disp(['The sub_key ' sub_key ' has not been found'])
end

sub_key='1 2'
The sub_key 1 2 has been found in:
ans = 
    '1 2'
ans = 
    '1 2 4 5'


sub_key='5 4'
The sub_key 5 4 has been found in:
ans = 
    '1 2 4 5'
ans = 
    '4 5'


sub_key='1 1'
The sub_key 1 1 has not been found