N-gram token filter

Changes token text to an ngram. For example, you can use the n-gram token filter to change fox to [ f, fo, o, ox, x ].

Add to an analyzer

ngram can be added to any analyzer as a filter.

JSON

"analyzer": {
  "substring": {
    "type": "custom",
    "tokenizer": "standard",
    "filter": ["ngram"]
  }
}

Configurable parameters

• min_gram (Optional, integer) Minimum length of characters in a gram. Defaults to 1.
• max_gram (Optional, integer) Maximum length of characters in a gram. Defaults to 2.
• preserve_original (Optional, Boolean) Emits original token when set to true. Defaults to false.

For example a 1 to 3 character edge-ngram could be configured and used like this:

JSON

"settings": {
  "analysis": {
    "analyzer": {
      "custom_analyzer": {
        "type": "custom",
        "filter": ["1_3_ngrams"]
      }
    },
    "filter": {
      "1_3_ngrams": {
        "type": "ngram",
        "min_gram": 1,
        "max_gram": 3
      }
    }
  }
}