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diff --git a/docs/content/en/functions/union.md b/docs/content/en/functions/union.md new file mode 100644 index 000000000..5c93e4bc7 --- /dev/null +++ b/docs/content/en/functions/union.md @@ -0,0 +1,49 @@ +--- +title: union +# linktitle: union +description: Given two arrays or slices, returns a new array that contains the elements or objects that belong to either or both arrays/slices. +godocref: +date: 2017-02-01 +publishdate: 2017-02-01 +lastmod: 2017-03-12 +categories: [functions] +menu: + docs: + parent: "functions" +keywords: [filtering,lists] +signature: ["union SET1 SET2"] +workson: [] +hugoversion: 0.20 +relatedfuncs: [intersect,where] +deprecated: false +aliases: [] +--- + +Given two arrays (or slices) A and B, this function will return a new array that contains the elements or objects that belong to either A or to B or to both. The elements supported are strings, integers, and floats (only float64). + +``` +{{ union (slice 1 2 3) (slice 3 4 5) }} +<!-- returns [1 2 3 4 5] --> + +{{ union (slice 1 2 3) nil }} +<!-- returns [1 2 3] --> + +{{ union nil (slice 1 2 3) }} +<!-- returns [1 2 3] --> + +{{ union nil nil }} +<!-- returns an error because both arrays/slices have to be of the same type --> +``` + + +This is also very useful to use as `OR` filters when combined with where: + +``` +{{ $pages := where .Site.RegularPages "Type" "not in" (slice "page" "about") }} +{{ $pages := $pages | union (where .Site.RegularPages "Params.pinned" true) }} +{{ $pages := $pages | intersect (where .Site.RegularPages "Params.images" "!=" nil) }} +``` + +The above fetches regular pages not of `page` or `about` type unless they are pinned. And finally, we exclude all pages with no `images` set in Page params. + +See [intersect](/functions/intersect) for `AND`. |