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Elastic Docs ›Elasticsearch Guide [2.3] ›Analysis ›Tokenizers

Pattern Tokenizer

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Pattern Tokenizer

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A tokenizer of type pattern that can flexibly separate text into terms via a regular expression. Accepts the following settings:

Setting Description

pattern

The regular expression pattern, defaults to \W+.

flags

The regular expression flags.

group

Which group to extract into tokens. Defaults to -1 (split).

IMPORTANT: The regular expression should match the token separators, not the tokens themselves.

Note that you may need to escape pattern string literal according to your client language rules. For example, in many programming languages a string literal for \W+ pattern is written as "\\W+". There is nothing special about pattern (you may have to escape other string literals as well); escaping pattern is common just because it often contains characters that should be escaped.

group set to -1 (the default) is equivalent to "split". Using group >= 0 selects the matching group as the token. For example, if you have:

pattern = '([^']+)'
group   = 0
input   = aaa 'bbb' 'ccc'

the output will be two tokens: 'bbb' and 'ccc' (including the ' marks). With the same input but using group=1, the output would be: bbb and ccc (no ' marks).

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