In
computer programming, an
enumerated type (also called
enumeration or
enum, or
factor in the
R programming language, and a
categorical variable in statistics) is a
data type consisting of a set of named
values called
elements,
members,
enumeral, or
enumerators of the type. The enumerator names are usually
identifiers that behave as
constants in the language. A
variable that has been
declared as having an enumerated type can be assigned any of the enumerators as a value. In other words, an enumerated type has values that are different from each other, and that can be compared and assigned, but which are not specified by the programmer as having any particular concrete representation in the computer's memory; compilers and interpreters can represent them arbitrarily.