diff --git a/_analyzers/token-filters/index.md b/_analyzers/token-filters/index.md index 21b4c3c7fa..a25acf6ec4 100644 --- a/_analyzers/token-filters/index.md +++ b/_analyzers/token-filters/index.md @@ -36,7 +36,7 @@ Token filter | Underlying Lucene token filter| Description [`keep_words`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/keep-words/) | [KeepWordFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/KeepWordFilter.html) | Checks the tokens against the specified word list and keeps only those that are in the list. [`keyword_marker`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/keyword-marker/) | [KeywordMarkerFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/KeywordMarkerFilter.html) | Marks specified tokens as keywords, preventing them from being stemmed. `keyword_repeat` | [KeywordRepeatFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/KeywordRepeatFilter.html) | Emits each incoming token twice: once as a keyword and once as a non-keyword. -`kstem` | [KStemFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/en/KStemFilter.html) | Provides kstem-based stemming for the English language. Combines algorithmic stemming with a built-in dictionary. +[`kstem`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/kstem/) | [KStemFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/en/KStemFilter.html) | Provides KStem-based stemming for the English language. Combines algorithmic stemming with a built-in dictionary. `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`]({{site.url}}{{site.baseurl}}/analyzers/token-filters/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. For example, document field value sizes can be limited based on the token count. diff --git a/_analyzers/token-filters/kstem.md b/_analyzers/token-filters/kstem.md new file mode 100644 index 0000000000..d13fd2c675 --- /dev/null +++ b/_analyzers/token-filters/kstem.md @@ -0,0 +1,92 @@ +--- +layout: default +title: KStem +parent: Token filters +nav_order: 220 +--- + +# KStem token filter + +The `kstem` token filter is a stemming filter used to reduce words to their root forms. The filter is a lightweight algorithmic stemmer designed for the English language that performs the following stemming operations: + +- Reduces plurals to their singular form. +- Converts different verb tenses to their base form. +- Removes common derivational endings, such as "-ing" or "-ed". + +The `kstem` token filter is equivalent to the a `stemmer` filter configured with a `light_english` language. It provides a more conservative stemming compared to other stemming filters like `porter_stem`. + +The `kstem` token filter is based on the Lucene KStemFilter. For more information, see the [Lucene documentation](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/en/KStemFilter.html). + +## Example + +The following example request creates a new index named `my_kstem_index` and configures an analyzer with a `kstem` filter: + +```json +PUT /my_kstem_index +{ + "settings": { + "analysis": { + "filter": { + "kstem_filter": { + "type": "kstem" + } + }, + "analyzer": { + "my_kstem_analyzer": { + "type": "custom", + "tokenizer": "standard", + "filter": [ + "lowercase", + "kstem_filter" + ] + } + } + } + }, + "mappings": { + "properties": { + "content": { + "type": "text", + "analyzer": "my_kstem_analyzer" + } + } + } +} +``` +{% include copy-curl.html %} + +## Generated tokens + +Use the following request to examine the tokens generated using the analyzer: + +```json +POST /my_kstem_index/_analyze +{ + "analyzer": "my_kstem_analyzer", + "text": "stops stopped" +} +``` +{% include copy-curl.html %} + +The response contains the generated tokens: + +```json +{ + "tokens": [ + { + "token": "stop", + "start_offset": 0, + "end_offset": 5, + "type": "", + "position": 0 + }, + { + "token": "stop", + "start_offset": 6, + "end_offset": 13, + "type": "", + "position": 1 + } + ] +} +``` \ No newline at end of file