Merge commit 'e509cac533600cf4fa8382c9cdab78ddd82db688'

docs/content/en/functions/collections/Complement.md

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+---
+title: collections.Complement
+linkTitle: complement
+description: Returns the elements of the last collection that are not in any of the others.
+categories: [functions]
+keywords: []
+menu:
+  docs:
+    parent: functions
+function:
+  aliases: [complement]
+  returnType: any
+  signatures: ['collections.Complement COLLECTION [COLLECTION]...']
+relatedFunctions:
+  - collections.Complement
+  - collections.Intersect
+  - collections.SymDiff
+  - collections.Union
+aliases: [/functions/complement]
+---
+
+To find the elements within `$c3` that do not exist in `$c1` or `$c2`:
+
+```go-html-template
+{{ $c1 := slice 3 }}
+{{ $c2 := slice 4 5 }}
+{{ $c3 := slice 1 2 3 4 5 }}
+
+{{ complement $c1 $c2 $c3 }} → [1 2]
+```
+
+{{% note %}}
+Make your code simpler to understand by using a [chained pipeline]:
+
+[chained pipeline]: https://pkg.go.dev/text/template#hdr-Pipelines
+{{% /note %}}
+
+
+```go-html-template
+{{ $c3 | complement $c1 $c2 }} → [1 2]
+```
+
+You can also use the `complement` function with page collections. Let's say your site has five content types:
+
+```text
+content/
+├── blog/
+├── books/
+├── faqs/
+├── films/
+└── songs/
+```
+
+To list everything except blog articles (`blog`) and frequently asked questions (`faqs`):
+
+```go-html-template
+{{ $blog := where site.RegularPages "Type" "blog" }}
+{{ $faqs := where site.RegularPages "Type" "faqs" }}
+{{ range site.RegularPages | complement $blog $faqs }}
+  <a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a>
+{{ end }}
+```
+
+{{% note %}}
+Although the example above demonstrates the `complement` function, you could use the [`where`] function as well:
+
+[`where`]: /functions/collections/where
+{{% /note %}} 
+
+```go-html-template
+{{ range where site.RegularPages "Type" "not in" (slice "blog" "faqs") }}
+  <a href="{{ .RelPermalink }}">{{ .LinkTitle }}</a>
+{{ end }}
+```
+
+In this example we use the `complement` function to remove [stop words] from a sentence:
+
+```go-html-template
+{{ $text := "The quick brown fox jumps over the lazy dog" }}
+{{ $stopWords := slice "a" "an" "in" "over" "the" "under" }}
+{{ $filtered := split $text " " | complement $stopWords }}
+
+{{ delimit $filtered " " }} → The quick brown fox jumps lazy dog
+```
+
+[stop words]: https://en.wikipedia.org/wiki/Stop_word