A single character value. For quantitative parameters, valid
choices are "double" and "integer" while for qualitative factors they are
"character" and "logical".
range
A two-element list of vector with the lowest or largest possible
values, respectively. If these cannot be set when the parameter is defined,
the unknown() function can be used. If a transformation is specified,
these values should be in the transformed units.
inclusive
A two-element logical vector for whether the the range
values should be inclusive or exclusive.
default
A single value the same class as type for the default
parameter value. unknown() can also be used here.
A vector of possible values that is required when type is
"character" or "logical" but optional otherwise.
label
An optional named character string that can be used for
printing and plotting. The named should reflect the object name (e.g.
"mtry", "neighbors", etc.)
Value
An object of class "param" with the primary class being either
"quant_param" or "qual_param". The range element of the object is always
converted to a list with elements "lower" and "upper". '