Edge N-gram token filter

Forms an N-gram of a specified length from the beginning of a token.

For example, you can use the edge_ngram token filter to change quick to qu.

Add to an analyzer

edge_ngram can be added to any analyzer as a filter.

JSON

"analyzer": {
  "longer_autocomplete_analyzer": {
    "type": "custom",
    "tokenizer": "standard",
    "filter": ["edge_ngram"]
  }
}

Configurable parameters

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

For example a 3-5 edge-ngram could be configured and used like this:

JSON

"settings": {
  "analysis": {
    "analyzer": {
      "custom_analyzer": {
        "type": "custom",
        "filter": ["3_5_edgegrams"]
      }
    },
    "filter": {
      "3_5_edgegrams": {
        "type": "edge_ngram",
        "min_gram": 3,
        "max_gram": 5
      }
    }
  }
}