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
}
]
}