Count Aggregates in clingo

Question

Test data

addEmployee(EmplID, Name1, Name2, TypeOfWork, Salary, TxnDate)
addEmployee("tjb1998", "eva", "mcdowell", "ra", 55000, 20).
addEmployee("tjb1987x", "ben", "xena", "cdt", 68000, q50).
addEmployee("tjb2112", "ryoko", "hakubi", "ra", 63000, 60).
addEmployee("tjb1987", "ben", "croshaw", "cdt", 68000, 90).
addEmployee("tjb3300m", "amane", "mauna", "ma", 61000, 105).

I want to group by employees as per the type of work and count of employees for the particular type of work. e.g:

ra 4
cdt 2
ma 1

below is the query I am trying to run

employee(TOW) :- addEmployee(_,_,_,TOW,_,_).
nmbrEmployeesOfSameType (N) :- N = #count { employee(TOW) }.

Please advise, I am at the beginner level for Clingo

Answer 1

Try this:

addEmployee("tjb1998", "eva", "mcdowell", "ra", 55000, 20).
addEmployee("tjb1987x", "ben", "xena", "cdt", 68000, q50).
addEmployee("tjb2112", "ryoko", "hakubi", "ra", 63000, 60).
addEmployee("tjb1987", "ben", "croshaw", "cdt", 60000, 90).
addEmployee("tjb3300m", "amane", "mauna", "ma", 61000, 105).


getType(P, X) :- addEmployee(X, _, _, P, _, _).

type(P) :- addEmployee(_, _, _, P, _, _).

result(P, S) :- S = #count{ I : getType(P,I)}, type(P).

#show result/2.

And the output will look like:

clingo version 4.5.3
Reading from test.lp
Solving...
Answer: 1
result("ra",2) result("cdt",2) result("ma",1)
SATISFIABLE

You can also copy my code and run it here to see if it works.