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Add Normalization token filter docs #8239 #8255

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2 changes: 1 addition & 1 deletion _analyzers/token-filters/index.md
Original file line number Diff line number Diff line change
Expand Up @@ -42,7 +42,7 @@ Token filter | Underlying Lucene token filter| Description
`min_hash` | [MinHashFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/minhash/MinHashFilter.html) | Uses the [MinHash technique](https://en.wikipedia.org/wiki/MinHash) to estimate document similarity. Performs the following operations on a token stream sequentially: <br> 1. Hashes each token in the stream. <br> 2. Assigns the hashes to buckets, keeping only the smallest hashes of each bucket. <br> 3. Outputs the smallest hash from each bucket as a token stream.
`multiplexer` | N/A | Emits multiple tokens at the same position. Runs each token through each of the specified filter lists separately and outputs the results as separate tokens.
`ngram` | [NGramTokenFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ngram/NGramTokenFilter.html) | Tokenizes the given token into n-grams of lengths between `min_gram` and `max_gram`.
Normalization | `arabic_normalization`: [ArabicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ar/ArabicNormalizer.html) <br> `german_normalization`: [GermanNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/de/GermanNormalizationFilter.html) <br> `hindi_normalization`: [HindiNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/hi/HindiNormalizer.html) <br> `indic_normalization`: [IndicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/in/IndicNormalizer.html) <br> `sorani_normalization`: [SoraniNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ckb/SoraniNormalizer.html) <br> `persian_normalization`: [PersianNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/fa/PersianNormalizer.html) <br> `scandinavian_normalization` : [ScandinavianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianNormalizationFilter.html) <br> `scandinavian_folding`: [ScandinavianFoldingFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianFoldingFilter.html) <br> `serbian_normalization`: [SerbianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/sr/SerbianNormalizationFilter.html) | Normalizes the characters of one of the listed languages.
[Normalization]({{site.url}}{{site.baseurl}}/analyzers/token-filters/normalization/) | `arabic_normalization`: [ArabicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ar/ArabicNormalizer.html) <br> `german_normalization`: [GermanNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/de/GermanNormalizationFilter.html) <br> `hindi_normalization`: [HindiNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/hi/HindiNormalizer.html) <br> `indic_normalization`: [IndicNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/in/IndicNormalizer.html) <br> `sorani_normalization`: [SoraniNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/ckb/SoraniNormalizer.html) <br> `persian_normalization`: [PersianNormalizer](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/fa/PersianNormalizer.html) <br> `scandinavian_normalization` : [ScandinavianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianNormalizationFilter.html) <br> `scandinavian_folding`: [ScandinavianFoldingFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/miscellaneous/ScandinavianFoldingFilter.html) <br> `serbian_normalization`: [SerbianNormalizationFilter](https://lucene.apache.org/core/9_10_0/analysis/common/org/apache/lucene/analysis/sr/SerbianNormalizationFilter.html) | Normalizes the characters of one of the listed languages.
`pattern_capture` | N/A | Generates a token for every capture group in the provided regular expression. Uses [Java regular expression syntax](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html).
`pattern_replace` | N/A | Matches a pattern in the provided regular expression and replaces matching substrings. Uses [Java regular expression syntax](https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html).
`phonetic` | N/A | Uses a phonetic encoder to emit a metaphone token for each token in the token stream. Requires installing the `analysis-phonetic` plugin.
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88 changes: 88 additions & 0 deletions _analyzers/token-filters/normalization.md
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---
layout: default
title: Normalization
parent: Token filters
nav_order: 300
---

# Normalization token filter

The `normalization` token filter is designed to adjust and simplify text in a way that reduces variations, particularly with special characters. It is primarily used to handle variations in writing by standardizing characters in specific languages.
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The following `normalization` token filters are available:

- [arabic_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/ar/ArabicNormalizer.html)
- [german_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/de/GermanNormalizationFilter.html)
- [hindi_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/hi/HindiNormalizer.html)
- [indic_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/in/IndicNormalizer.html)
- [sorani_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/ckb/SoraniNormalizer.html)
- [persian_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/fa/PersianNormalizer.html)
- [scandinavian_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/miscellaneous/ScandinavianNormalizationFilter.html)
- [scandinavian_folding](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/miscellaneous/ScandinavianFoldingFilter.html)
- [serbian_normalization](https://lucene.apache.org/core/8_7_0/analyzers-common/org/apache/lucene/analysis/sr/SerbianNormalizationFilter.html)


## Example

The following example request creates a new index named `german_normalizer_example` and configures an analyzer with a `german_normalization` filter:

```json
PUT /german_normalizer_example
{
"settings": {
"analysis": {
"filter": {
"german_normalizer": {
"type": "german_normalization"
}
},
"analyzer": {
"german_normalizer_analyzer": {
"tokenizer": "standard",
"filter": [
"lowercase",
"german_normalizer"
]
}
}
}
}
}
```
{% include copy-curl.html %}

## Generated tokens

Use the following request to examine the tokens generated using the analyzer:

```json
POST /german_normalizer_example/_analyze
{
"text": "Straße München",
"analyzer": "german_normalizer_analyzer"
}
```
{% include copy-curl.html %}

The response contains the generated tokens:

```json
{
"tokens": [
{
"token": "strasse",
"start_offset": 0,
"end_offset": 6,
"type": "<ALPHANUM>",
"position": 0
},
{
"token": "munchen",
"start_offset": 7,
"end_offset": 14,
"type": "<ALPHANUM>",
"position": 1
}
]
}
```
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