OpenSearch/docs/plugins/analysis-stempel.asciidoc

[[analysis-stempel]]
=== Stempel Polish Analysis Plugin

The Stempel Analysis plugin integrates Lucene's Stempel analysis
module for Polish into elasticsearch.

It provides high quality stemming for Polish, based on the
http://www.egothor.org/[Egothor project].

:plugin_name: analysis-stempel
include::install_remove.asciidoc[]

[[analysis-stempel-tokenizer]]
[discrete]
==== `stempel` tokenizer and token filters

The plugin provides the `polish` analyzer and the `polish_stem` and `polish_stop` token filters,
which are not configurable.

==== Reimplementing and extending the analyzers

The `polish` analyzer could be reimplemented as a `custom` analyzer that can
then be extended and configured differently as follows:

[source,console]
----------------------------------------------------
PUT /stempel_example
{
  "settings": {
    "analysis": {
      "analyzer": {
        "rebuilt_stempel": {
          "tokenizer":  "standard",
          "filter": [
            "lowercase",
            "polish_stop",
            "polish_stem"
          ]
        }
      }
    }
  }
}
----------------------------------------------------
// TEST[s/\n$/\nstartyaml\n  - compare_analyzers: {index: stempel_example, first: polish, second: rebuilt_stempel}\nendyaml\n/]

[[analysis-polish-stop]]
==== `polish_stop` token filter

The `polish_stop` token filter filters out Polish stopwords (`_polish_`), and
any other custom stopwords specified by the user. This filter only supports
the predefined `_polish_` stopwords list.  If you want to use a different
predefined list, then use the
{ref}/analysis-stop-tokenfilter.html[`stop` token filter] instead.

[source,console]
--------------------------------------------------
PUT /polish_stop_example
{
  "settings": {
    "index": {
      "analysis": {
        "analyzer": {
          "analyzer_with_stop": {
            "tokenizer": "standard",
            "filter": [
              "lowercase",
              "polish_stop"
            ]
          }
        },
        "filter": {
          "polish_stop": {
            "type": "polish_stop",
            "stopwords": [
              "_polish_",
              "jeść"
            ]
          }
        }
      }
    }
  }
}

GET polish_stop_example/_analyze
{
  "analyzer": "analyzer_with_stop",
  "text": "Gdzie kucharek sześć, tam nie ma co jeść."
}
--------------------------------------------------

The above request returns:

[source,console-result]
--------------------------------------------------
{
  "tokens" : [
    {
      "token" : "kucharek",
      "start_offset" : 6,
      "end_offset" : 14,
      "type" : "<ALPHANUM>",
      "position" : 1
    },
    {
      "token" : "sześć",
      "start_offset" : 15,
      "end_offset" : 20,
      "type" : "<ALPHANUM>",
      "position" : 2
    }
  ]
}
--------------------------------------------------