elasticsearch/docs/reference/text-analysis/analysis-reverse-tokenfilter.md

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navigation_title: "Reverse" mapped_pages:

• https://www.elastic.co/guide/en/elasticsearch/reference/current/analysis-reverse-tokenfilter.html ---

Reverse token filter [analysis-reverse-tokenfilter]

Reverses each token in a stream. For example, you can use the reverse filter to change cat to tac.

Reversed tokens are useful for suffix-based searches, such as finding words that end in -ion or searching file names by their extension.

This filter uses Lucene’s ReverseStringFilter.

Example [analysis-reverse-tokenfilter-analyze-ex]

The following analyze API request uses the reverse filter to reverse each token in quick fox jumps:

GET _analyze
{
  "tokenizer" : "standard",
  "filter" : ["reverse"],
  "text" : "quick fox jumps"
}

The filter produces the following tokens:

[ kciuq, xof, spmuj ]

Add to an analyzer [analysis-reverse-tokenfilter-analyzer-ex]

The following create index API request uses the reverse filter to configure a new custom analyzer.

PUT reverse_example
{
  "settings" : {
    "analysis" : {
      "analyzer" : {
        "whitespace_reverse" : {
          "tokenizer" : "whitespace",
          "filter" : ["reverse"]
        }
      }
    }
  }
}