REBOL 3 Functions: union

union set1 set2 /case /skip size

Returns the union of two data sets.

Arguments:

set1 [block! string! binary! bitset! typeset!] - first set

set2 [block! string! binary! bitset! typeset!] - second set

Refinements:

/case - Use case-sensitive comparison

/skip - Treat the series as records of fixed size

size [integer!]

Description

Returns all elements present within two blocks or strings ignoring the duplicates.

lunch: [ham cheese bread carrot]
dinner: [ham salad carrot rice]
probe union lunch dinner
[ham cheese bread carrot salad rice]

probe sort union [1 3 2 4] [3 5 4 6]
[1 2 3 4 5 6]

string1: "CBDA"    ; A B C D scrambled
string2: "EDCF"    ; C D E F scrambled
probe sort union string1 string2
"ABCDEF"

items: [1 1 2 3 2 4 5 1 2]
probe union items items  ; get unique set
[1 2 3 4 5]

str: "abcacbaabcca"
probe union str str
"abc"

To obtain a unique set (to remove duplicate values) you can use UNIQUE.

Note that performing this function over very large data sets can be CPU intensive.