KDB: set difference

Question

How can one find set (data structure) difference in KDB? Example:

a: 1 2 3 4
b: 2 3

expected result: 1 4. Simple guesses like a-b or a _ b do not work.

Thank you very much for your help!

Answer 1

You're after the keyword except

q)a:1 2 3 4;b:2 3
q)a except b
1 4