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Document classification

Document classification determines what the document text is about by mapping it to the nodes of a taxonomy.

Resources performing document classification have paths like this:

categorize/taxonomy/language

Boxed parts are placeholders.

In the reference section of this manual you will find all the information you need to perform document classification using the API's RESTful interface, specifically:

Even if you use the API through a client that hides the REST interface, whether it is made by you or is one of those made available by expert.ai, the last piece of information is useful because it helps you to find out what data the API returns.

Here is an example of performing document classification on a short English test:

This example is based on the Python client you can find on GitHub.

The client gets user credentials from two environment variables:

EAI_USERNAME
EAI_PASSWORD

Set those variables with you account credentials before running the sample program below.

The program prints the list of categories.

from expertai.nlapi.cloud.client import ExpertAiClient
client = ExpertAiClient()

text = "Michael Jordan was one of the best basketball players of all time. Scoring was Jordan's stand-out skill, but he still holds a defensive NBA record, with eight steals in a half."
taxonomy = 'iptc'
language= 'en'

output = client.classification(body={"document": {"text": text}}, params={'taxonomy': taxonomy, 'language': language})

print("Tab separated list of categories:")

for category in output.categories:
    print(category.id_, category.hierarchy, sep="\t")

This example is based on the Java client you can find on GitHub.

The client gets user credentials from two environment variables:

EAI_USERNAME
EAI_PASSWORD

Set those variables with you account credentials before running the sample program below.

The program prints the JSON response.

import ai.expert.nlapi.security.Authentication;
import ai.expert.nlapi.security.Authenticator;
import ai.expert.nlapi.security.BasicAuthenticator;
import ai.expert.nlapi.security.DefaultCredentialsProvider;
import ai.expert.nlapi.v2.API;
import ai.expert.nlapi.v2.Categorizer;
import ai.expert.nlapi.v2.CategorizerConfig;
import ai.expert.nlapi.v2.message.CategorizeResponse;
import ai.expert.nlapi.v2.model.CategorizeDocument;

public class Main {

    public static Authentication createAuthentication() throws Exception {
        DefaultCredentialsProvider credentialsProvider = new DefaultCredentialsProvider();
        Authenticator authenticator = new BasicAuthenticator(credentialsProvider);
        return new Authentication(authenticator);
    }

    public static Categorizer createCategorizer() throws Exception {
        return new Categorizer(CategorizerConfig.builder()
                                                .withVersion(API.Versions.V2)
                                                .withTaxonomy("iptc")
                                                .withLanguage(API.Languages.en)
                                                .withAuthentication(createAuthentication())
                                                .build());
    }

    public static void main(String[] args) {
        try {
            String text = "Michael Jordan was one of the best basketball players of all time. Scoring was Jordan's stand-out skill, but he still holds a defensive NBA record, with eight steals in a half.";

            Categorizer categorizer = createCategorizer();

            CategorizeResponse categorization = categorizer.categorize(text);


            // Output JSON representation

            System.out.println("JSON representation:");
            categorization.prettyPrint();


            // Tab separated list of categories.

            System.out.println("Tab separated list of categories:");
            CategorizeDocument data = categorization.getData();

            data.getCategories().stream().forEach(c -> System.out.println(c.getId() + "\t" + c.getHierarchy()));
        }
        catch(Exception ex) {
            ex.printStackTrace();
        }
    }
}

The following curl command posts a document to the document classification resource of the API's REST interface.
Run the command from a shell after replacing token with the actual authorization token.

curl -X POST https://nlapi.expert.ai/v2/categorize/iptc/en \
    -H 'Authorization: Bearer token' \
    -H 'Content-Type: application/json; charset=utf-8' \
    -d '{
  "document": {
    "text": "Michael Jordan was one of the best basketball players of all time. Scoring was Jordan'\''s stand-out skill, but he still holds a defensive NBA record, with eight steals in a half."
  }
}'

The server returns a JSON object.

The following curl command posts a document to the document classification resource of the API's REST interface.
Open a command prompt in the folder where you installed curl and run the command after replacing token with the actual authorization token.

curl -X POST https://nlapi.expert.ai/v2/categorize/iptc/en  -H "Authorization: Bearer token" -H "Content-Type: application/json; charset=utf-8" -d "{\"document\": {\"text\": \"Michael Jordan was one of the best basketball players of all time. Scoring was Jordan's stand-out skill, but he still holds a defensive NBA record, with eight steals in a half.\"}}"

The server returns a JSON object.