SDDATA Constructor for data set object

      A=SDDATA(DATA)
      A=SDDATA(DATA,LAB)

 INPUT
    DATA     Data matrix samples times features (double precision)
    LAB      Sample labels (SDLAB object, char array or cell array)

 OUTPUT
    A        SDDATA object

 DESCRIPTION
 SDDATA object represents a data set. Data matrix DATA contains samples
 in rows and features in columns. When sample labels LAB are not
 provided, SDDATA will assign all samples to 'unknown' class.

 BASIC OPERATIONS
  +A                       return data matrix (shorthand for double(A))
  A(1:10)                  return with first 10 samples
  A(:,[2 4])               return all samples and features 2 and 4
  A(:,:,3)                 return 3rd class
  A(:,:,{'apple','lemon'}) return subset with named classes
  A.lab                    return sample labels
  A.featlab                return feature labels
  A.patient=sdlab(patname) create patient labels

 SEE ALSO
 SDLAB, GETLAB, SETLAB, SUBSET, RANDSUBSET