Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

[DOCS] Reformat remove_duplicates token filter #53608

Merged
merged 2 commits into from
Mar 16, 2020
Merged
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Original file line number Diff line number Diff line change
Expand Up @@ -4,5 +4,151 @@
<titleabbrev>Remove duplicates</titleabbrev>
++++

A token filter of type `remove_duplicates` that drops identical tokens at the
same position.
Removes duplicate tokens in the same position.

The `remove_duplicates` filter uses Lucene's
{lucene-analysis-docs}/miscellaneous/RemoveDuplicatesTokenFilter.html[RemoveDuplicatesTokenFilter].

[[analysis-remove-duplicates-tokenfilter-analyze-ex]]
==== Example

To see how the `remove_duplicates` filter works, you first need to produce a
token stream containing duplicate tokens in the same position.

The following <<indices-analyze,analyze API>> request uses the
<<analysis-keyword-repeat-tokenfilter,`keyword_repeat`>> and
<<analysis-stemmer-tokenfilter,`stemmer`>> filters to create stemmed and
unstemmed tokens for `jumping dog`.

[source,console]
----
GET _analyze
{
"tokenizer": "whitespace",
"filter": [
"keyword_repeat",
"stemmer"
],
"text": "jumping dog"
}
----

The API returns the following response. Note that the `dog` token in position
`1` is duplicated.

[source,console-result]
----
{
"tokens": [
{
"token": "jumping",
"start_offset": 0,
"end_offset": 7,
"type": "word",
"position": 0
},
{
"token": "jump",
"start_offset": 0,
"end_offset": 7,
"type": "word",
"position": 0
},
{
"token": "dog",
"start_offset": 8,
"end_offset": 11,
"type": "word",
"position": 1
},
{
"token": "dog",
"start_offset": 8,
"end_offset": 11,
"type": "word",
"position": 1
}
]
}
----

To remove one of the duplicate `dog` tokens, add the `remove_duplicates` filter
to the previous analyze API request.

[source,console]
----
GET _analyze
{
"tokenizer": "whitespace",
"filter": [
"keyword_repeat",
"stemmer",
"remove_duplicates"
],
"text": "jumping dog"
}
----

The API returns the following response. There is now only one `dog` token in
position `1`.

[source,console-result]
----
{
"tokens": [
{
"token": "jumping",
"start_offset": 0,
"end_offset": 7,
"type": "word",
"position": 0
},
{
"token": "jump",
"start_offset": 0,
"end_offset": 7,
"type": "word",
"position": 0
},
{
"token": "dog",
"start_offset": 8,
"end_offset": 11,
"type": "word",
"position": 1
}
]
}
----

[[analysis-remove-duplicates-tokenfilter-analyzer-ex]]
==== Add to an analyzer

The following <<indices-create-index,create index API>> request uses the
`remove_duplicates` filter to configure a new <<analysis-custom-analyzer,custom
analyzer>>.

This custom analyzer uses the `keyword_repeat` and `stemmer` filters to create a
stemmed and unstemmed version of each token in a stream. The `remove_duplicates`
filter then removes any duplicate tokens in the same position.

[source,console]
----
PUT my_index
{
"settings": {
"analysis": {
"analyzer": {
"my_custom_analyzer": {
"tokenizer": "standard",
"filter": [
"keyword_repeat",
"stemmer",
"remove_duplicates"
]
}
}
}
}
}
----