Sample data:
(def coocurrences
[["foo" "bar" 3]
["bar" "foo" 3]
["foo" "quux" 6]
["quux" "foo" 6]
["bar" "quux" 2]
["quux" "bar" 2]])
Query:
(require '[cascalog.api :refer :all] '[cascalog.ops :as c])
(let [total (<- [?key-a ?sum]
(coocurrences ?key-a _ ?c)
(c/sum ?c :> ?sum))]
(?<- (stdout) [?key-a ?key-b ?prob]
(div ?c ?sum :> ?prob)
(coocurrences ?key-a ?key-b ?c)
(total ?key-a ?sum)))
Output:
RESULTS
-----------------------
bar foo 0.6
bar quux 0.4
foo bar 0.3333333333333333
foo quux 0.6666666666666666
quux foo 0.75
quux bar 0.25
-----------------------