Enumerations

For a long list containing few distinct values, an enumeration can reduce storage requirements. The ‘manual’ way to create an enum (for understanding, not recommended):

q)y:`a`b`c`b`a`b`c`c`c`c`c`c`c
q)x:`a`b`c
q)show e:"i"$x?y;
0 1 2 1 0 1 2 2 2 2 2 2 2i  /these values are what we store instead of y.
q)x e                       /get back the symbols any time from x and e.
`a`b`c`b`a`b`c`c`c`c`c`c`c
q)`x!e / same result as `x$y 
`x$`a`b`c`b`a`b`c`c`c`c`c`c`c

Create, extend and resolve enumerations using these operators:

operator	name	semantics
$	Enumerate	create an enumeration
?	Enum Extend	extend an enumeration
!	Enumeration	resolve values from an enumeration

Q for Mortals §7.5 Enumerations