Defining a factor on DataFrames

hpoit · November 12, 2016, 5:03pm

Hello! Would anyone know how to define a factor on DataFrames according to

liang456/Stanford-Probabilistic-Graphical-Models-Coursera/blob/master/PGM_Programming_Assignment_1/FactorProduct.m#L14


      
          %   The factor data structure has the following fields:

          %       .var    Vector of variables in the factor, e.g. [1 2 3]

          %       .card   Vector of cardinalities corresponding to .var, e.g. [2 2 2]

          %       .val    Value table of size prod(.card)

          %

          %   See also FactorMarginalization.m, IndexToAssignment.m, and

          %   AssignmentToIndex.m

          

          function C = FactorProduct(A, B)

          

          % Check for empty factors

          if (isempty(A.var)), C = B; return; end;

          if (isempty(B.var)), C = A; return; end;

          

          % Check that variables in both A and B have the same cardinality

          [dummy iA iB] = intersect(A.var, B.var);

          if ~isempty(dummy)

          	% A and B have at least 1 variable in common

          	assert(all(A.card(iA) == B.card(iB)), 'Dimensionality mismatch in factors');

          end

nalimilan · November 13, 2016, 10:07am

“Factor” has many different meanings, so I think you’ll have to be more explicit. Though if it’s used in the R sense, have a look at PooledDataArray in the DataArrays package. There’s also CategoricalArray in the eponymous package, which will be used by the next DataFrames release.