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Elastic Docs ›Elasticsearch Guide [2.4] ›Analysis ›Tokenizers

NGram Tokenizer

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NGram Tokenizer

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A tokenizer of type nGram.

The following are settings that can be set for a nGram tokenizer type:

Setting Description Default value

min_gram

Minimum size in codepoints of a single n-gram

1.

max_gram

Maximum size in codepoints of a single n-gram

2.

token_chars

Characters classes to keep in the tokens, Elasticsearch will split on characters that don’t belong to any of these classes.

[] (Keep all characters)

token_chars accepts the following character classes:

letter

for example a, b, ï or 京

digit

for example 3 or 7

whitespace

for example " " or "\n"

punctuation

for example ! or "

symbol

for example $ or √

Example

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    curl -XPUT 'localhost:9200/test' -d '
    {
        "settings" : {
            "analysis" : {
                "analyzer" : {
                    "my_ngram_analyzer" : {
                        "tokenizer" : "my_ngram_tokenizer"
                    }
                },
                "tokenizer" : {
                    "my_ngram_tokenizer" : {
                        "type" : "nGram",
                        "min_gram" : "2",
                        "max_gram" : "3",
                        "token_chars": [ "letter", "digit" ]
                    }
                }
            }
        }
    }'

    curl 'localhost:9200/test/_analyze?pretty=1&analyzer=my_ngram_analyzer' -d 'FC Schalke 04'
    # FC, Sc, Sch, ch, cha, ha, hal, al, alk, lk, lke, ke, 04
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