Method Encode can be used to apply binary encoding. Referring to the result as z, binary encoding takes each category in the nominal variable x, and creates a column in z containing all zeros and ones. A value of zero indicates that this category was not present and a value of one indicates that it is present.

For example, if x[]={2,1,3,4,2,4} then nClasses=4, and

Unfiltering can be performed using the method Decode. In this case, z is the input, and we refer to x as the output. Binary unfiltering takes binary representation in z, and returns the appropriate class in x.

For example, if a row in z equals {0, 1, 0, 0}, then the return value from Decode would be 2 for that row. If a row in z equals {1,0,0,0}, then the return value from Decode would be 1 for that row. Notice these are the same values as the first two elements of the original x because classes are numbered sequentially from 1 to nClasses. This ensures that the results of Decode are associated with the i-th class in x.