Create an extended factor
factor_ext(x, values, levels, drop = FALSE)The object to convert to an factor_ext
The values used for the levels; This is were factor_ext is different from a
factor, as values for levels do not have to be consecutive or start at 1.
The levels of the object; character string
Should non-occurring levels be dropped
An object of S3 class factor_ext
An extended version of a regular factor variable. Instead of the levels having values from
1 to n where n is the number of levels, any integer value can be used for any level (including 64bit integers). If
all values are in the range of a regular 32-bit integer, it is coerced to int. Automatic coercion of extended factors
to factors in H5ToR_Post for enums only works for 32-bit integer base types.
In this page this is heavily used, as constants in HDF5 can be arbitrary integer values.