Lowercase token filteredit
Changes token text to lowercase. For example, you can use the lowercase filter
to change THE Lazy DoG to the lazy dog.
In addition to a default filter, the lowercase token filter provides access to
Lucene’s language-specific lowercase filters for Greek, Irish, and Turkish.
Exampleedit
The following analyze API request uses the default
lowercase filter to change the THE Quick FoX JUMPs to lowercase:
GET _analyze
{
"tokenizer" : "standard",
"filter" : ["lowercase"],
"text" : "THE Quick FoX JUMPs"
}
The filter produces the following tokens:
[ the, quick, fox, jumps ]
Add to an analyzeredit
The following create index API request uses the
lowercase filter to configure a new
custom analyzer.
PUT lowercase_example
{
"settings": {
"analysis": {
"analyzer": {
"whitespace_lowercase": {
"tokenizer": "whitespace",
"filter": [ "lowercase" ]
}
}
}
}
}
Configurable parametersedit
-
language -
(Optional, string) Language-specific lowercase token filter to use. Valid values include:
-
greek - Uses Lucene’s GreekLowerCaseFilter
-
irish - Uses Lucene’s IrishLowerCaseFilter
-
turkish - Uses Lucene’s TurkishLowerCaseFilter
If not specified, defaults to Lucene’s LowerCaseFilter.
-
Customizeedit
To customize the lowercase filter, duplicate it to create the basis
for a new custom token filter. You can modify the filter using its configurable
parameters.
For example, the following request creates a custom lowercase filter for the
Greek language:
PUT custom_lowercase_example
{
"settings": {
"analysis": {
"analyzer": {
"greek_lowercase_example": {
"type": "custom",
"tokenizer": "standard",
"filter": ["greek_lowercase"]
}
},
"filter": {
"greek_lowercase": {
"type": "lowercase",
"language": "greek"
}
}
}
}
}