You're viewing version 2.18 of the OpenSearch documentation. This version is no longer maintained. For the latest version, see the current documentation. For information about OpenSearch version maintenance, see Release Schedule and Maintenance Policy.
Keep words token filter
The keep_words token filter is designed to keep only certain words during the analysis process. This filter is useful if you have a large body of text but are only interested in certain keywords or terms.
Parameters
The keep_words token filter can be configured with the following parameters.
| Parameter | Required/Optional | Data type | Description |
|---|---|---|---|
keep_words | Required if keep_words_path is not configured | List of strings | The list of words to keep. |
keep_words_path | Required if keep_words is not configured | String | The path to the file containing the list of words to keep. |
keep_words_case | Optional | Boolean | Whether to lowercase all words during comparison. Default is false. |
Example
The following example request creates a new index named my_index and configures an analyzer with a keep_words filter:
PUT my_index
{
"settings": {
"analysis": {
"analyzer": {
"custom_keep_word": {
"tokenizer": "standard",
"filter": [ "keep_words_filter" ]
}
},
"filter": {
"keep_words_filter": {
"type": "keep",
"keep_words": ["example", "world", "opensearch"],
"keep_words_case": true
}
}
}
}
}
Generated tokens
Use the following request to examine the tokens generated using the analyzer:
GET /my_index/_analyze
{
"analyzer": "custom_keep_word",
"text": "Hello, world! This is an OpenSearch example."
}
The response contains the generated tokens:
{
"tokens": [
{
"token": "world",
"start_offset": 7,
"end_offset": 12,
"type": "<ALPHANUM>",
"position": 1
},
{
"token": "OpenSearch",
"start_offset": 25,
"end_offset": 35,
"type": "<ALPHANUM>",
"position": 5
},
{
"token": "example",
"start_offset": 36,
"end_offset": 43,
"type": "<ALPHANUM>",
"position": 6
}
]
}