How to delete repeated elements in column

I have 10x4 array with strings say

D={'Run'  ''     'play'     '';
    ''    'go'    ''       'sit' ;  
    'Run' ''      'play'    '';
    ''    'go'      ''     'sit';
    ''    'down'    ''     'play';
    ''    'go'      ''     'sit'}

I want to remove consecutive elements in each column such that i get result as

res={'Run'  ''     'play'     '';
    ''    'go'      ''       'sit'  ; 
    ''     ''      ''         '';
    ''    ''        ''        '';
    ''    'down'    ''       'play';
    ''    'go'      ''       'sit'}

I tried using for loop and deleting ,the thing is that all elements with same names get deleted.

Kindly help

[Image Analyst]

Why? What's the use case for this request?

[Pat]

i want to remove consecutive duplicates for next stage of processing

Answer 1

[Azzi Abdelmalek]

D={'Run'  ''     'play'     '';
  ''    'go'    ''       'sit' ;  
  'Run' ''      'play'    '';
  ''    'go'      ''     'sit';
  ''    'down'    ''     'play';
  ''    'go'      ''     'sit'}
ii=unique(D);
v=0:numel(ii);
b=cellfun(@(x) v(ismember(ii,x)),D);
[n,m]=size(D);
c=b;
for l=1:m
  for k=2:n
      q=b(1:k-1,l);
      idx=find(q,1,'last');
      if b(k,l)==q(idx) ;
          c(k,l)=0;
      end
  end
end
out=ii(c+1)

[Pat]

Thanks Azzi,it helped me a lot.can u suggest a book for matlab programming