Function Factor to transform a continue value to a limited number of different values

[Seddryck]

The function factor is used to encode a value as a factor (the terms ‘category’ and ‘enumerated type’ are also used for factors). The factor levels are assumed to be ordered.

factor(
  "Baby"     =? {[age] ?| less-than(1)},  
  "Children" =? {[age] ?| less-than(12)},  
  "Teenager" =? {[age] ?| less-than(18)},  
  "Teenager" =? {{[age] ?| less-than(21)} |AND {[continent] ?| equivalent-to("America")}},
  "Adult"
)