kuromoji_stemmer token filter

The kuromoji_stemmer token filter normalizes common katakana spelling variations ending in a long sound character by removing this character (U+30FC). Only full-width katakana characters are supported.

This token filter accepts the following setting:

minimum_length
Katakana words shorter than the minimum length are not stemmed (default is 4).
PUT kuromoji_sample
{
  "settings": {
    "index": {
      "analysis": {
        "analyzer": {
          "my_analyzer": {
            "tokenizer": "kuromoji_tokenizer",
            "filter": [
              "my_katakana_stemmer"
            ]
          }
        },
        "filter": {
          "my_katakana_stemmer": {
            "type": "kuromoji_stemmer",
            "minimum_length": 4
          }
        }
      }
    }
  }
}

GET kuromoji_sample/_analyze
{
  "analyzer": "my_analyzer",
  "text": "コピー" 
}

GET kuromoji_sample/_analyze
{
  "analyzer": "my_analyzer",
  "text": "サーバー" 
}

Returns コピー.

Return サーバ.