12 juin 2020

Combinaisons de paires uniques

Pour obtenir toutes les paires uniques à partir d’une séquence.

seq = ("a", "b", "c", "d")
result = 
.   a,b  a,c  a,d
.    .   b,c  b,d
.    .    .   c,d
.    .    .    .

• voir aussi How do I get the total number of unique pairs of a set in the database?

XQuery

xquery version "3.1" ;
(:~
 : Pairs combinations in a sequence
 : Unique pairs in a sequence (where order is irrelevant)
 :)
let $seq := ("a", "b", "b", "d")
for $i at $pos in $seq
for $j in fn:subsequence($seq, $pos+1, fn:count($seq))
return <result>{$i, $j}</result>

(: result :)
a,b
a,c
a,d
b,c
b,d
c,d