Fingerprint token filter
editFingerprint token filter
editSorts and removes duplicate tokens from a token stream, then concatenates the stream into a single output token.
For example, this filter changes the [ the, fox, was, very, very, quick ]
token stream as follows:
-
Sorts the tokens alphabetically to
[ fox, quick, the, very, very, was ]
-
Removes a duplicate instance of the
very
token. -
Concatenates the token stream to a output single token:
[fox quick the very was ]
Output tokens produced by this filter are useful for fingerprinting and clustering a body of text as described in the OpenRefine project.
This filter uses Lucene’s FingerprintFilter.
Example
editThe following analyze API request uses the fingerprint
filter to create a single output token for the text zebra jumps over resting
resting dog
:
response = client.indices.analyze( body: { tokenizer: 'whitespace', filter: [ 'fingerprint' ], text: 'zebra jumps over resting resting dog' } ) puts response
GET _analyze { "tokenizer" : "whitespace", "filter" : ["fingerprint"], "text" : "zebra jumps over resting resting dog" }
The filter produces the following token:
[ dog jumps over resting zebra ]
Add to an analyzer
editThe following create index API request uses the
fingerprint
filter to configure a new custom
analyzer.
PUT fingerprint_example { "settings": { "analysis": { "analyzer": { "whitespace_fingerprint": { "tokenizer": "whitespace", "filter": [ "fingerprint" ] } } } } }
Configurable parameters
editCustomize
editTo customize the fingerprint
filter, duplicate it to create the basis
for a new custom token filter. You can modify the filter using its configurable
parameters.
For example, the following request creates a custom fingerprint
filter with
that use +
to concatenate token streams. The filter also limits
output tokens to 100
characters or fewer.
response = client.indices.create( index: 'custom_fingerprint_example', body: { settings: { analysis: { analyzer: { whitespace_: { tokenizer: 'whitespace', filter: [ 'fingerprint_plus_concat' ] } }, filter: { fingerprint_plus_concat: { type: 'fingerprint', max_output_size: 100, separator: '+' } } } } } ) puts response
PUT custom_fingerprint_example { "settings": { "analysis": { "analyzer": { "whitespace_": { "tokenizer": "whitespace", "filter": [ "fingerprint_plus_concat" ] } }, "filter": { "fingerprint_plus_concat": { "type": "fingerprint", "max_output_size": 100, "separator": "+" } } } } }