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--- | ||
layout: default | ||
title: Keep types | ||
parent: Token filters | ||
nav_order: 180 | ||
--- | ||
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# Keep types token filter | ||
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The `keep_types` token filter is a type of token filter used in text analysis to control which token types are kept or discarded. Different tokenizers produce different token types, for example, `<HOST>`, `<NUM>`, or `<ALPHANUM>`. | ||
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The `keyword`, `simple_pattern`, and `simple_pattern_split` tokenizers do not support the `keep_types` token filter because these tokenizers do not support token type attributes. | ||
{: .note} | ||
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## Parameters | ||
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The `keep_types` token filter can be configured with the following parameters. | ||
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Parameter | Required/Optional | Data type | Description | ||
:--- | :--- | :--- | :--- | ||
`types` | Required | List of strings | List of token types to be kept or discarded (determined by the `mode`). | ||
`mode`| Optional | String | Whether to `include` or `exclude` the token types specified in `types`. Default is `include`. | ||
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## Example | ||
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The following example request creates a new index named `test_index` and configures an analyzer with a `keep_types` filter: | ||
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```json | ||
PUT /test_index | ||
{ | ||
"settings": { | ||
"analysis": { | ||
"analyzer": { | ||
"custom_analyzer": { | ||
"type": "custom", | ||
"tokenizer": "standard", | ||
"filter": ["lowercase", "keep_types_filter"] | ||
} | ||
}, | ||
"filter": { | ||
"keep_types_filter": { | ||
"type": "keep_types", | ||
"types": ["<ALPHANUM>"] | ||
} | ||
} | ||
} | ||
} | ||
} | ||
``` | ||
{% include copy-curl.html %} | ||
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## Generated tokens | ||
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Use the following request to examine the tokens generated using the analyzer: | ||
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```json | ||
GET /test_index/_analyze | ||
{ | ||
"analyzer": "custom_analyzer", | ||
"text": "Hello 2 world! This is an example." | ||
} | ||
``` | ||
{% include copy-curl.html %} | ||
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The response contains the generated tokens: | ||
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```json | ||
{ | ||
"tokens": [ | ||
{ | ||
"token": "hello", | ||
"start_offset": 0, | ||
"end_offset": 5, | ||
"type": "<ALPHANUM>", | ||
"position": 0 | ||
}, | ||
{ | ||
"token": "world", | ||
"start_offset": 8, | ||
"end_offset": 13, | ||
"type": "<ALPHANUM>", | ||
"position": 2 | ||
}, | ||
{ | ||
"token": "this", | ||
"start_offset": 15, | ||
"end_offset": 19, | ||
"type": "<ALPHANUM>", | ||
"position": 3 | ||
}, | ||
{ | ||
"token": "is", | ||
"start_offset": 20, | ||
"end_offset": 22, | ||
"type": "<ALPHANUM>", | ||
"position": 4 | ||
}, | ||
{ | ||
"token": "an", | ||
"start_offset": 23, | ||
"end_offset": 25, | ||
"type": "<ALPHANUM>", | ||
"position": 5 | ||
}, | ||
{ | ||
"token": "example", | ||
"start_offset": 26, | ||
"end_offset": 33, | ||
"type": "<ALPHANUM>", | ||
"position": 6 | ||
} | ||
] | ||
} | ||
``` |