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ICU normalization token filter

Normalizes characters as explained here. It registers itself as the icu_normalizer token filter, which is available to all indices without any further configuration. The type of normalization can be specified with the name parameter, which accepts nfc, nfkc, and nfkc_cf (default).

Which letters are normalized can be controlled by specifying the unicode_set_filter parameter, which accepts a UnicodeSet.

You should probably prefer the Normalization character filter.

Here are two examples, the default usage and a customised token filter:

 PUT icu_sample { "settings": { "index": { "analysis": { "analyzer": { "nfkc_cf_normalized": { "tokenizer": "icu_tokenizer", "filter": [ "icu_normalizer" ] }, "nfc_normalized": { "tokenizer": "icu_tokenizer", "filter": [ "nfc_normalizer" ] } }, "filter": { "nfc_normalizer": { "type": "icu_normalizer", "name": "nfc" } } } } } }
  1. Uses the default nfkc_cf normalization.
  2. Uses the customized nfc_normalizer token filter, which is set to use nfc normalization.