Mapping character filter

The mapping character filter accepts a map of keys and values. Whenever it encounters a string of characters that is the same as a key, it replaces them with the value associated with that key.

Matching is greedy; the longest pattern matching at a given point wins. Replacements are allowed to be the empty string.

The mapping filter uses Lucene’s MappingCharFilter.

Example

The following analyze API request uses the mapping filter to convert Hindu-Arabic numerals (٠‎١٢٣٤٥٦٧٨‎٩‎) into their Arabic-Latin equivalents (0123456789), changing the text My license plate is ٢٥٠١٥ to My license plate is 25015.

  1. GET /_analyze
  2. {
  3.   "tokenizer": "keyword",
  4.   "char_filter": [
  5.     {
  6.       "type": "mapping",
  7.       "mappings": [
  8.         "٠ => 0",
  9.         "١ => 1",
  10.         "٢ => 2",
  11.         "٣ => 3",
  12.         "٤ => 4",
  13.         "٥ => 5",
  14.         "٦ => 6",
  15.         "٧ => 7",
  16.         "٨ => 8",
  17.         "٩ => 9"
  18.       ]
  19.     }
  20.   ],
  21.   "text": "My license plate is ٢٥٠١٥"
  22. }

The filter produces the following text:

  1. [ My license plate is 25015 ]

Configurable parameters

mappings

(Required*, array of strings) Array of mappings, with each element having the form key => value.

Either this or the mappings_path parameter must be specified.

mappings_path

(Required*, string) Path to a file containing key => value mappings.

This path must be absolute or relative to the config location, and the file must be UTF-8 encoded. Each mapping in the file must be separated by a line break.

Either this or the mappings parameter must be specified.

Customize and add to an analyzer

To customize the mappings filter, duplicate it to create the basis for a new custom character filter. You can modify the filter using its configurable parameters.

The following create index API request configures a new custom analyzer using a custom mappings filter, my_mappings_char_filter.

The my_mappings_char_filter filter replaces the :) and :( emoticons with a text equivalent.

  1. PUT /my-index-000001
  2. {
  3.   "settings": {
  4.     "analysis": {
  5.       "analyzer": {
  6.         "my_analyzer": {
  7.           "tokenizer": "standard",
  8.           "char_filter": [
  9.             "my_mappings_char_filter"
  10.           ]
  11.         }
  12.       },
  13.       "char_filter": {
  14.         "my_mappings_char_filter": {
  15.           "type": "mapping",
  16.           "mappings": [
  17.             ":) => _happy_",
  18.             ":( => _sad_"
  19.           ]
  20.         }
  21.       }
  22.     }
  23.   }
  24. }

The following analyze API request uses the custom my_mappings_char_filter to replace :( with _sad_ in the text I'm delighted about it :(.

  1. GET /my-index-000001/_analyze
  2. {
  3.   "tokenizer": "keyword",
  4.   "char_filter": [ "my_mappings_char_filter" ],
  5.   "text": "I'm delighted about it :("
  6. }

The filter produces the following text:

  1. [ I'm delighted about it _sad_ ]