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The Gazetteer Lookup Extraction index stage (called the Gazetteer Lookup Extractor stage in versions earlier than 3.0) uses predefined lists of words and phrases to process specified text fields in a document. A gazetteer is a set of lookup lists over names of people, places, or things. These lookup lists are used to find occurrences of these names in text. The matched items are saved into separate fields on the document for downstream processing.

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Gazetteers and OpenNLP Tools

The following video shows how to configure a Gazetteer Lookup Extraction stage in combination with OpenNLP:

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Uploading Lookup Lists to Lucidworks Search Blob Store

Lucidworks Search includes a number of lookup lists in the directory at https://EXAMPLE_COMPANY.lucidworks.cloud/data/nlp/gazetteer. To use the supplied lists or a list of your own data, each must list be uploaded to Lucidworks Search using the Blob Store API in order to make the list contents available to the Gazetteer Lookup Extraction stage. For example, to identify color names, you would first compile a list of color terms, one entry per line in a text file with suffix .lst and then upload that file using the Lucidworks Search REST API endpoint api/blobs/<listfilename>, as per the following example which uses the curl command-line utility, where ‘admin’ is the name of a user with admin privileges, and ‘pass’ is that user’s password: 
curl -u USERNAME:PASSWORD -X PUT --data-binary @data/nlp/gazetteer/colors.lst -H 'Content-type: text/plain' http://EXAMPLE_COMPANY.lucidworks.cloud/api/blobs/colors.lst
Replace EXAMPLE_COMPANY with the name provided by your Lucidworks representative.

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Name Lookup Example

Define a lookup-extractor to identify mentions of certain celebrities in text field description_t: 
{
  "type" : "lookup-extractor",
  "id" : "peopleLookup",
  "rules" : [ {
    "source" : [ "description_t" ],
    "target" : "celebrities_ss",
    "entityTypes" : [ {
      "name" : "person_female",
      "definitions" : [ "person_female.lst" ]
    } ],
    "additionalEntities" : [ {
      "name" : "players",
      "definitions" : [ "sharapova", "murray" ]
    }, {
      "name" : "actors",
      "definitions" : [ "pitt", "jolie" ]
    } ],
    "caseSensitive" : false
  } ],
  "skip" : false
}

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Configuration

When entering configuration values in the UI, use unescaped characters, such as \t for the tab character. When entering configuration values in the API, use escaped characters, such as \\t for the tab character.