How do I merge two datasets that contains missing values in Statistics Toolbox 7.2 (R2009b)?

I want to merge to the following DATASETs and only display necessary information:

D1 = dataset('XLSFile','Ex.xls','Sheet',1,'ReadVarNames',false)

 D1 = 

     Var1       Var2

     'A'         1  

     'B'         2  

     'C'         3  

     'E'        11  

     'H'        17  

D2 = dataset('XLSFile','Ex.xls','Sheet',2,'ReadVarNames',false)

 D2 = 

     Var1       Var2

     'A'        4   

     'B'        5   

     'D'        6   

     'E'        7

Answer 1

[MathWorks Support Team]

The following example shows how to JOIN the two DATASETs containing missing values and then display only the necessary information:

%%Read data from file as dataset classes

D1 = dataset('XLSFile','Ex.xls','Sheet',1,'ReadVarNames',false);

D2 = dataset('XLSFile','Ex.xls','Sheet',2,'ReadVarNames',false);

%%Join the datasets

J = join(D1,D2,'type','outer','keys','Var1');

%%Look for missing variables

missing = strcmp(J.Var1_left,'');

% Fill in missing values

J.Var1_left(missing) = J.Var1_right(missing);

%%Reduce dataset to show only necessary information

J = dataset(J.Var1_left,J.Var2_left,J.Var2_right) %#ok

%%Convert NaN's to 0 (if necessary)

J.Var2(isnan(J.Var2)) = 0;

J.Var3(isnan(J.Var3)) = 0 %#ok