[DOCS] Reformat `word_delimiter` token filter (#53387)
Makes the following changes to the `word_delimiter` token filter docs: * Adds a warning admonition recommending the `word_delimiter_graph` filter instead. This warning includes a link to the deprecated Lucene `WordDelimiterFilter`. * Updates the description * Adds detailed analyze snippet * Adds custom analyzer and custom filter snippets * Reorganizes and updates parameter documentation
This commit is contained in:
James Rodewig
GitHub
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<titleabbrev>Word delimiter</titleabbrev>
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++++
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Named `word_delimiter`, it Splits words into subwords and performs
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optional transformations on subword groups. Words are split into
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subwords with the following rules:
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[WARNING]
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====
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We recommend using the
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<<analysis-word-delimiter-graph-tokenfilter,`word_delimiter_graph`>> instead of
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the `word_delimiter` filter.
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* split on intra-word delimiters (by default, all non alpha-numeric
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characters): "Wi-Fi" -> "Wi", "Fi"
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* split on case transitions: "PowerShot" -> "Power", "Shot"
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* split on letter-number transitions: "SD500" -> "SD", "500"
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* leading and trailing intra-word delimiters on each subword are
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ignored: "//hello---there, 'dude'" -> "hello", "there", "dude"
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* trailing "'s" are removed for each subword: "O'Neil's" -> "O", "Neil"
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The `word_delimiter` filter can produce invalid token graphs. See
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<<analysis-word-delimiter-graph-differences>>.
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Parameters include:
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The `word_delimiter` filter also uses Lucene's
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{lucene-analysis-docs}/miscellaneous/WordDelimiterFilter.html[WordDelimiterFilter],
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which is marked as deprecated.
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====
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`generate_word_parts`::
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If `true` causes parts of words to be
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generated: "Power-Shot", "(Power,Shot)" -> "Power" "Shot". Defaults to `true`.
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Splits tokens at non-alphanumeric characters. The `word_delimiter` filter
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also performs optional token normalization based on a set of rules. By default,
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the filter uses the following rules:
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`generate_number_parts`::
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If `true` causes number subwords to be
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generated: "500-42" -> "500" "42". Defaults to `true`.
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* Split tokens at non-alphanumeric characters.
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The filter uses these characters as delimiters.
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For example: `Super-Duper` -> `Super`, `Duper`
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* Remove leading or trailing delimiters from each token.
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For example: `XL---42+'Autocoder'` -> `XL`, `42`, `Autocoder`
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* Split tokens at letter case transitions.
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For example: `PowerShot` -> `Power`, `Shot`
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* Split tokens at letter-number transitions.
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For example: `XL500` -> `XL`, `500`
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* Remove the English possessive (`'s`) from the end of each token.
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For example: `Neil's` -> `Neil`
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`catenate_words`::
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If `true` causes maximum runs of word parts to be
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catenated: "wi-fi" -> "wifi". Defaults to `false`.
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[TIP]
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====
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The `word_delimiter` filter was designed to remove punctuation from complex
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identifiers, such as product IDs or part numbers. For these use cases, we
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recommend using the `word_delimiter` filter with the
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<<analysis-keyword-tokenizer,`keyword`>> tokenizer.
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`catenate_numbers`::
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If `true` causes maximum runs of number parts to
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be catenated: "500-42" -> "50042". Defaults to `false`.
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Avoid using the `word_delimiter` filter to split hyphenated words, such as
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`wi-fi`. Because users often search for these words both with and without
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hyphens, we recommend using the
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<<analysis-synonym-graph-tokenfilter,`synonym_graph`>> filter instead.
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====
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[[analysis-word-delimiter-tokenfilter-analyze-ex]]
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==== Example
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The following <<indices-analyze,analyze API>> request uses the
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`word_delimiter` filter to split `Neil's-Super-Duper-XL500--42+AutoCoder`
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into normalized tokens using the filter's default rules:
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[source,console]
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----
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GET /_analyze
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{
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"tokenizer": "keyword",
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"filter": [ "word_delimiter" ],
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"text": "Neil's-Super-Duper-XL500--42+AutoCoder"
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}
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----
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The filter produces the following tokens:
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[source,txt]
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----
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[ Neil, Super, Duper, XL, 500, 42, Auto, Coder ]
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----
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////
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[source,console-result]
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----
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{
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"tokens": [
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{
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"token": "Neil",
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"start_offset": 0,
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"end_offset": 4,
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"type": "word",
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"position": 0
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},
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{
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"token": "Super",
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"start_offset": 7,
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"end_offset": 12,
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"type": "word",
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"position": 1
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},
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{
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"token": "Duper",
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"start_offset": 13,
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"end_offset": 18,
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"type": "word",
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"position": 2
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},
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{
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"token": "XL",
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"start_offset": 19,
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"end_offset": 21,
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"type": "word",
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"position": 3
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},
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{
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"token": "500",
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"start_offset": 21,
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"end_offset": 24,
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"type": "word",
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"position": 4
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},
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{
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"token": "42",
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"start_offset": 26,
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"end_offset": 28,
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"type": "word",
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"position": 5
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},
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{
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"token": "Auto",
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"start_offset": 29,
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"end_offset": 33,
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"type": "word",
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"position": 6
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},
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{
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"token": "Coder",
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"start_offset": 33,
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"end_offset": 38,
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"type": "word",
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"position": 7
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}
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]
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}
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----
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////
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[analysis-word-delimiter-tokenfilter-analyzer-ex]]
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==== Add to an analyzer
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The following <<indices-create-index,create index API>> request uses the
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`word_delimiter` filter to configure a new
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<<analysis-custom-analyzer,custom analyzer>>.
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[source,console]
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----
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PUT /my_index
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{
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"settings": {
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"analysis": {
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"analyzer": {
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"my_analyzer": {
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"tokenizer": "keyword",
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"filter": [ "word_delimiter" ]
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}
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}
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}
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}
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}
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----
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[WARNING]
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====
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Avoid using the `word_delimiter` filter with tokenizers that remove punctuation,
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such as the <<analysis-standard-tokenizer,`standard`>> tokenizer. This could
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prevent the `word_delimiter` filter from splitting tokens correctly. It can also
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interfere with the filter's configurable parameters, such as `catenate_all` or
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`preserve_original`. We recommend using the
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<<analysis-keyword-tokenizer,`keyword`>> or
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<<analysis-whitespace-tokenizer,`whitespace`>> tokenizer instead.
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====
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[[word-delimiter-tokenfilter-configure-parms]]
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==== Configurable parameters
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`catenate_all`::
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If `true` causes all subword parts to be catenated:
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"wi-fi-4000" -> "wifi4000". Defaults to `false`.
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+
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--
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(Optional, boolean)
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If `true`, the filter produces catenated tokens for chains of alphanumeric
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characters separated by non-alphabetic delimiters. For example:
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`super-duper-xl-500` -> [ `super`, **`superduperxl500`**, `duper`, `xl`, `500`
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]. Defaults to `false`.
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`split_on_case_change`::
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If `true` causes "PowerShot" to be two tokens;
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("Power-Shot" remains two parts regards). Defaults to `true`.
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[WARNING]
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====
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When used for search analysis, catenated tokens can cause problems for the
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<<query-dsl-match-query-phrase,`match_phrase`>> query and other queries that
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rely on token position for matching. Avoid setting this parameter to `true` if
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you plan to use these queries.
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====
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--
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`catenate_numbers`::
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+
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--
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(Optional, boolean)
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If `true`, the filter produces catenated tokens for chains of numeric characters
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separated by non-alphabetic delimiters. For example: `01-02-03` ->
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[ `01`, **`010203`**, `02`, `03` ]. Defaults to `false`.
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[WARNING]
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====
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When used for search analysis, catenated tokens can cause problems for the
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<<query-dsl-match-query-phrase,`match_phrase`>> query and other queries that
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rely on token position for matching. Avoid setting this parameter to `true` if
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you plan to use these queries.
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====
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--
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`catenate_words`::
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+
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--
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(Optional, boolean)
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If `true`, the filter produces catenated tokens for chains of alphabetical
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characters separated by non-alphabetic delimiters. For example: `super-duper-xl`
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-> [ `super`, **`superduperxl`**, `duper`, `xl` ]. Defaults to `false`.
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[WARNING]
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====
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When used for search analysis, catenated tokens can cause problems for the
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<<query-dsl-match-query-phrase,`match_phrase`>> query and other queries that
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rely on token position for matching. Avoid setting this parameter to `true` if
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you plan to use these queries.
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====
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--
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`generate_number_parts`::
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(Optional, boolean)
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If `true`, the filter includes tokens consisting of only numeric characters in
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the output. If `false`, the filter excludes these tokens from the output.
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Defaults to `true`.
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`generate_word_parts`::
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(Optional, boolean)
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If `true`, the filter includes tokens consisting of only alphabetical characters
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in the output. If `false`, the filter excludes these tokens from the output.
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Defaults to `true`.
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`preserve_original`::
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If `true` includes original words in subwords:
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"500-42" -> "500-42" "500" "42". Defaults to `false`.
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`split_on_numerics`::
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If `true` causes "j2se" to be three tokens; "j"
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"2" "se". Defaults to `true`.
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`stem_english_possessive`::
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If `true` causes trailing "'s" to be
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removed for each subword: "O'Neil's" -> "O", "Neil". Defaults to `true`.
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Advance settings include:
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(Optional, boolean)
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If `true`, the filter includes the original version of any split tokens in the
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output. This original version includes non-alphanumeric delimiters. For example:
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`super-duper-xl-500` -> [ **`super-duper-xl-500`**, `super`, `duper`, `xl`,
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`500` ]. Defaults to `false`.
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`protected_words`::
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A list of protected words from being delimiter.
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Either an array, or also can set `protected_words_path` which resolved
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to a file configured with protected words (one on each line).
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Automatically resolves to `config/` based location if exists.
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(Optional, array of strings)
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Array of tokens the filter won't split.
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`protected_words_path`::
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+
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--
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(Optional, string)
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Path to a file that contains a list of tokens the filter won't split.
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This path must be absolute or relative to the `config` location, and the file
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must be UTF-8 encoded. Each token in the file must be separated by a line
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break.
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--
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`split_on_case_change`::
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(Optional, boolean)
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If `true`, the filter splits tokens at letter case transitions. For example:
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`camelCase` -> [ `camel`, `Case` ]. Defaults to `true`.
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`split_on_numerics`::
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(Optional, boolean)
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If `true`, the filter splits tokens at letter-number transitions. For example:
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`j2se` -> [ `j`, `2`, `se` ]. Defaults to `true`.
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`stem_english_possessive`::
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(Optional, boolean)
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If `true`, the filter removes the English possessive (`'s`) from the end of each
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token. For example: `O'Neil's` -> [ `O`, `Neil` ]. Defaults to `true`.
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`type_table`::
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A custom type mapping table, for example (when configured
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using `type_table_path`):
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+
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--
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(Optional, array of strings)
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Array of custom type mappings for characters. This allows you to map
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non-alphanumeric characters as numeric or alphanumeric to avoid splitting on
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those characters.
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[source,type_table]
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--------------------------------------------------
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# Map the $, %, '.', and ',' characters to DIGIT
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# This might be useful for financial data.
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$ => DIGIT
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% => DIGIT
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. => DIGIT
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\\u002C => DIGIT
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For example, the following array maps the plus (`+`) and hyphen (`-`) characters
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as alphanumeric, which means they won't be treated as delimiters:
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# in some cases you might not want to split on ZWJ
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# this also tests the case where we need a bigger byte[]
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# see http://en.wikipedia.org/wiki/Zero-width_joiner
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\\u200D => ALPHANUM
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--------------------------------------------------
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`[ "+ => ALPHA", "- => ALPHA" ]`
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NOTE: Using a tokenizer like the `standard` tokenizer may interfere with
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the `catenate_*` and `preserve_original` parameters, as the original
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string may already have lost punctuation during tokenization. Instead,
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you may want to use the `whitespace` tokenizer.
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Supported types include:
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* `ALPHA` (Alphabetical)
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* `ALPHANUM` (Alphanumeric)
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* `DIGIT` (Numeric)
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* `LOWER` (Lowercase alphabetical)
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* `SUBWORD_DELIM` (Non-alphanumeric delimiter)
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* `UPPER` (Uppercase alphabetical)
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--
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`type_table_path`::
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+
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--
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(Optional, string)
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Path to a file that contains custom type mappings for characters. This allows
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you to map non-alphanumeric characters as numeric or alphanumeric to avoid
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splitting on those characters.
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For example, the contents of this file may contain the following:
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[source,txt]
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----
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# Map the $, %, '.', and ',' characters to DIGIT
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# This might be useful for financial data.
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$ => DIGIT
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% => DIGIT
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. => DIGIT
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\\u002C => DIGIT
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# in some cases you might not want to split on ZWJ
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# this also tests the case where we need a bigger byte[]
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# see http://en.wikipedia.org/wiki/Zero-width_joiner
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\\u200D => ALPHANUM
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----
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Supported types include:
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* `ALPHA` (Alphabetical)
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* `ALPHANUM` (Alphanumeric)
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* `DIGIT` (Numeric)
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* `LOWER` (Lowercase alphabetical)
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* `SUBWORD_DELIM` (Non-alphanumeric delimiter)
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* `UPPER` (Uppercase alphabetical)
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This file path must be absolute or relative to the `config` location, and the
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file must be UTF-8 encoded. Each mapping in the file must be separated by a line
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break.
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--
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[[analysis-word-delimiter-tokenfilter-customize]]
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==== Customize
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To customize the `word_delimiter` filter, duplicate it to create the basis
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for a new custom token filter. You can modify the filter using its configurable
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parameters.
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For example, the following request creates a `word_delimiter`
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filter that uses the following rules:
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* Split tokens at non-alphanumeric characters, _except_ the hyphen (`-`)
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character.
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* Remove leading or trailing delimiters from each token.
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* Do _not_ split tokens at letter case transitions.
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* Do _not_ split tokens at letter-number transitions.
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* Remove the English possessive (`'s`) from the end of each token.
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[source,console]
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----
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PUT /my_index
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{
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"settings": {
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"analysis": {
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"analyzer": {
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"my_analyzer": {
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"tokenizer": "keyword",
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"filter": [ "my_custom_word_delimiter_filter" ]
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}
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},
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"filter": {
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"my_custom_word_delimiter_filter": {
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"type": "word_delimiter",
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"type_table": [ "- => ALPHA" ],
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"split_on_case_change": false,
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"split_on_numerics": false,
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"stem_english_possessive": true
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}
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}
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}
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}
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}
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----
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