How do you remove rows that contain a duplicate value within the same column of a cell array?

I need to remove the entire row within a cell array if a value within a column (in this example, the column (4) headed with d) is equal to the value within that same column in the following row, so that I am only left with one row containing that value in the column.

For example:

data=
{'a','b','c','d';
 'z','y', 1,  2;
 'z','y', 1,  2;
 'z','y', 1,  3;
 'z','y', 1,  3;
 'z','y', 1,  4;}

where a,b,c, and d are simply colummn headers

so that I am left with

newdata=
{'a','b','c','d';
 'z','y', 1,  2;
 'z','y', 1,  3;
 'z','y', 1,  4;}

Where in newdata, the duplicate values (2 and 3) in column 4, headed d, are removed, along with their entire corresponding row.

Answer 1

[Cedric]

I am answering as if you could have multiple consecutive rows with same values in column 4.

 % - Modified data set that tests "multiple.." as well.
 data = {'a','b','c','d'; 'z','m',1,2; 'z','n',1,2; 'z','o',1,2; ...
         'z','y',1,3; 'z','y',1,3; 'z','y',1,4} ;

 % - Build logical index vector of rows to keep based on differences in col 4.
 toKeep  =  [true; diff( cell2mat( data(2:end,4) )) ~= 0; true] ;

 % - Extract relevant rows.
 newData =  data(toKeep,:) ;

This produces

 >> newData
 newData = 

    'a'    'b'    'c'    'd'
    'z'    'o'    [1]    [2]
    'z'    'y'    [1]    [3]
    'z'    'y'    [1]    [4]

PS: and it is the same if you cannot have multiple consecutive rows with same values actually.