From e65268fece37744ea53f210a6f4d3aee33a827e7 Mon Sep 17 00:00:00 2001 From: "opensearch-trigger-bot[bot]" <98922864+opensearch-trigger-bot[bot]@users.noreply.github.com> Date: Mon, 2 Dec 2024 14:42:27 +0000 Subject: [PATCH] Add lowercase token filter docs (#8162) (#8834) --- _analyzers/token-filters/index.md | 2 +- _analyzers/token-filters/lowercase.md | 82 +++++++++++++++++++++++++++ 2 files changed, 83 insertions(+), 1 deletion(-) create mode 100644 _analyzers/token-filters/lowercase.md diff --git a/_analyzers/token-filters/index.md b/_analyzers/token-filters/index.md index 6ff348dd37..040397424b 100644 --- a/_analyzers/token-filters/index.md +++ b/_analyzers/token-filters/index.md @@ -40,7 +40,7 @@ Token filter | Underlying Lucene token filter| Description `kuromoji_completion` | [JapaneseCompletionFilter](https://lucene.apache.org/core/9_10_0/analysis/kuromoji/org/apache/lucene/analysis/ja/JapaneseCompletionFilter.html) | Adds Japanese romanized terms to the token stream (in addition to the original tokens). Usually used to support autocomplete on Japanese search terms. Note that the filter has a `mode` parameter, which should be set to `index` when used in an index analyzer and `query` when used in a search analyzer. Requires the `analysis-kuromoji` plugin. For information about installing the plugin, see [Additional plugins]({{site.url}}{{site.baseurl}}/install-and-configure/plugins/#additional-plugins). [`length`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/length/) | [LengthFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/LengthFilter.html) | Removes tokens that are shorter or longer than the length range specified by `min` and `max`. `limit` | [LimitTokenCountFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/LimitTokenCountFilter.html) | Limits the number of output tokens. A common use case is to limit the size of document field values based on token count. -`lowercase` | [LowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/LowerCaseFilter.html) | Converts tokens to lowercase. The default [LowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/LowerCaseFilter.html) is for the English language. You can set the `language` parameter to `greek` (uses [GreekLowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/el/GreekLowerCaseFilter.html)), `irish` (uses [IrishLowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ga/IrishLowerCaseFilter.html)), or `turkish` (uses [TurkishLowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/tr/TurkishLowerCaseFilter.html)). +[`lowercase`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/lowercase/) | [LowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/LowerCaseFilter.html) | Converts tokens to lowercase. The default [LowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/core/LowerCaseFilter.html) processes the English language. To process other languages, set the `language` parameter to `greek` (uses [GreekLowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/el/GreekLowerCaseFilter.html)), `irish` (uses [IrishLowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ga/IrishLowerCaseFilter.html)), or `turkish` (uses [TurkishLowerCaseFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/tr/TurkishLowerCaseFilter.html)). [`min_hash`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/min-hash/) | [MinHashFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/minhash/MinHashFilter.html) | Uses the [MinHash technique](https://en.wikipedia.org/wiki/MinHash) to estimate document similarity. Performs the following operations on a token stream sequentially:
1. Hashes each token in the stream.
2. Assigns the hashes to buckets, keeping only the smallest hashes of each bucket.
3. Outputs the smallest hash from each bucket as a token stream. [`multiplexer`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/multiplexer/) | N/A | Emits multiple tokens at the same position. Runs each token through each of the specified filter lists separately and outputs the results as separate tokens. [`ngram`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/ngram/) | [NGramTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ngram/NGramTokenFilter.html) | Tokenizes the given token into n-grams of lengths between `min_gram` and `max_gram`. diff --git a/_analyzers/token-filters/lowercase.md b/_analyzers/token-filters/lowercase.md new file mode 100644 index 0000000000..89f0f219fa --- /dev/null +++ b/_analyzers/token-filters/lowercase.md @@ -0,0 +1,82 @@ +--- +layout: default +title: Lowercase +parent: Token filters +nav_order: 260 +--- + +# Lowercase token filter + +The `lowercase` token filter is used to convert all characters in the token stream to lowercase, making searches case insensitive. + +## Parameters + +The `lowercase` token filter can be configured with the following parameter. + +Parameter | Required/Optional | Description +:--- | :--- | :--- + `language` | Optional | Specifies a language-specific token filter. Valid values are:
- [`greek`](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/el/GreekLowerCaseFilter.html)
- [`irish`](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/ga/IrishLowerCaseFilter.html)
- [`turkish`](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/tr/TurkishLowerCaseFilter.html).
Default is the [Lucene LowerCaseFilter](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/core/LowerCaseFilter.html). + +## Example + +The following example request creates a new index named `custom_lowercase_example`. It configures an analyzer with a `lowercase` filter and specifies `greek` as the `language`: + +```json +PUT /custom_lowercase_example +{ + "settings": { + "analysis": { + "analyzer": { + "greek_lowercase_example": { + "type": "custom", + "tokenizer": "standard", + "filter": ["greek_lowercase"] + } + }, + "filter": { + "greek_lowercase": { + "type": "lowercase", + "language": "greek" + } + } + } + } +} +``` +{% include copy-curl.html %} + +## Generated tokens + +Use the following request to examine the tokens generated using the analyzer: + +```json +GET /custom_lowercase_example/_analyze +{ + "analyzer": "greek_lowercase_example", + "text": "Αθήνα ΕΛΛΑΔΑ" +} +``` +{% include copy-curl.html %} + +The response contains the generated tokens: + +```json +{ + "tokens": [ + { + "token": "αθηνα", + "start_offset": 0, + "end_offset": 5, + "type": "", + "position": 0 + }, + { + "token": "ελλαδα", + "start_offset": 6, + "end_offset": 12, + "type": "", + "position": 1 + } + ] +} +```