Analyze sentiment in a string

Inspect the given text and identify the prevailing emotional opinion.

Explore further

For detailed documentation that includes this code sample, see the following:

• Analyzing Sentiment

Code sample

Go

To learn how to install and use the client library for Natural Language, see Natural Language client libraries. For more information, see the Natural Language Go API reference documentation.

To authenticate to Natural Language, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

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import (
	"context"
	"fmt"
	"io"

	language "cloud.google.com/go/language/apiv2"
	"cloud.google.com/go/language/apiv2/languagepb"
)

// analyzeSentiment sends a string of text to the Cloud Natural Language API to
// assess the sentiment of the text.
func analyzeSentiment(w io.Writer, text string) error {
	ctx := context.Background()

	// Initialize client.
	client, err := language.NewClient(ctx)
	if err != nil {
		return err
	}
	defer client.Close()

	resp, err := client.AnalyzeSentiment(ctx, &languagepb.AnalyzeSentimentRequest{
		Document: &languagepb.Document{
			Source: &languagepb.Document_Content{
				Content: text,
			},
			Type: languagepb.Document_PLAIN_TEXT,
		},
		EncodingType: languagepb.EncodingType_UTF8,
	})

	if err != nil {
		return fmt.Errorf("AnalyzeSentiment: %w", err)
	}
	fmt.Fprintf(w, "Response: %q\n", resp)

	return nil
}

Java

To learn how to install and use the client library for Natural Language, see Natural Language client libraries. For more information, see the Natural Language Java API reference documentation.

To authenticate to Natural Language, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

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// Instantiate the Language client com.google.cloud.language.v2.LanguageServiceClient
try (LanguageServiceClient language = LanguageServiceClient.create()) {
  Document doc = Document.newBuilder().setContent(text).setType(Type.PLAIN_TEXT).build();
  AnalyzeSentimentResponse response = language.analyzeSentiment(doc);
  Sentiment sentiment = response.getDocumentSentiment();
  if (sentiment == null) {
    System.out.println("No sentiment found");
  } else {
    System.out.printf("Sentiment magnitude: %.3f\n", sentiment.getMagnitude());
    System.out.printf("Sentiment score: %.3f\n", sentiment.getScore());
  }
  return sentiment;
}

Node.js

To learn how to install and use the client library for Natural Language, see Natural Language client libraries. For more information, see the Natural Language Node.js API reference documentation.

To authenticate to Natural Language, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

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// Imports the Google Cloud client library
const language = require('@google-cloud/language').v2;

// Creates a client
const client = new language.LanguageServiceClient();

/**
 * TODO(developer): Uncomment the following line to run this code.
 */
// const text = 'Your text to analyze, e.g. Hello, world!';

// Prepares a document, representing the provided text
const document = {
  content: text,
  type: 'PLAIN_TEXT',
};

// Detects the sentiment of the document
const [result] = await client.analyzeSentiment({document});

const sentiment = result.documentSentiment;
console.log('Document sentiment:');
console.log(`  Score: ${sentiment.score}`);
console.log(`  Magnitude: ${sentiment.magnitude}`);

const sentences = result.sentences;
sentences.forEach(sentence => {
  console.log(`Sentence: ${sentence.text.content}`);
  console.log(`  Score: ${sentence.sentiment.score}`);
  console.log(`  Magnitude: ${sentence.sentiment.magnitude}`);
});

PHP

To learn how to install and use the client library for Natural Language, see Natural Language client libraries.

To authenticate to Natural Language, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

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use Google\Cloud\Language\V1\AnalyzeSentimentRequest;
use Google\Cloud\Language\V1\Client\LanguageServiceClient;
use Google\Cloud\Language\V1\Document;
use Google\Cloud\Language\V1\Document\Type;

/**
 * @param string $text The text to analyze
 */
function analyze_sentiment(string $text): void
{
    $languageServiceClient = new LanguageServiceClient();

    // Create a new Document, add text as content and set type to PLAIN_TEXT
    $document = (new Document())
        ->setContent($text)
        ->setType(Type::PLAIN_TEXT);

    // Call the analyzeSentiment function
    $request = (new AnalyzeSentimentRequest())
        ->setDocument($document);
    $response = $languageServiceClient->analyzeSentiment($request);
    $document_sentiment = $response->getDocumentSentiment();
    // Print document information
    printf('Document Sentiment:' . PHP_EOL);
    printf('  Magnitude: %s' . PHP_EOL, $document_sentiment->getMagnitude());
    printf('  Score: %s' . PHP_EOL, $document_sentiment->getScore());
    printf(PHP_EOL);
    $sentences = $response->getSentences();
    foreach ($sentences as $sentence) {
        printf('Sentence: %s' . PHP_EOL, $sentence->getText()->getContent());
        printf('Sentence Sentiment:' . PHP_EOL);
        $sentiment = $sentence->getSentiment();
        if ($sentiment) {
            printf('Entity Magnitude: %s' . PHP_EOL, $sentiment->getMagnitude());
            printf('Entity Score: %s' . PHP_EOL, $sentiment->getScore());
        }
        print(PHP_EOL);
    }
}

Python

To learn how to install and use the client library for Natural Language, see Natural Language client libraries. For more information, see the Natural Language Python API reference documentation.

To authenticate to Natural Language, set up Application Default Credentials. For more information, see Set up authentication for a local development environment.

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from google.cloud import language_v2


def sample_analyze_sentiment(text_content: str = "I am so happy and joyful.") -> None:
    """
    Analyzes Sentiment in a string.

    Args:
      text_content: The text content to analyze.
    """

    client = language_v2.LanguageServiceClient()

    # text_content = 'I am so happy and joyful.'

    # Available types: PLAIN_TEXT, HTML
    document_type_in_plain_text = language_v2.Document.Type.PLAIN_TEXT

    # Optional. If not specified, the language is automatically detected.
    # For list of supported languages:
    # https://cloud.google.com/natural-language/docs/languages
    language_code = "en"
    document = {
        "content": text_content,
        "type_": document_type_in_plain_text,
        "language_code": language_code,
    }

    # Available values: NONE, UTF8, UTF16, UTF32
    # See https://cloud.google.com/natural-language/docs/reference/rest/v2/EncodingType.
    encoding_type = language_v2.EncodingType.UTF8

    response = client.analyze_sentiment(
        request={"document": document, "encoding_type": encoding_type}
    )
    # Get overall sentiment of the input document
    print(f"Document sentiment score: {response.document_sentiment.score}")
    print(f"Document sentiment magnitude: {response.document_sentiment.magnitude}")
    # Get sentiment for all sentences in the document
    for sentence in response.sentences:
        print(f"Sentence text: {sentence.text.content}")
        print(f"Sentence sentiment score: {sentence.sentiment.score}")
        print(f"Sentence sentiment magnitude: {sentence.sentiment.magnitude}")

    # Get the language of the text, which will be the same as
    # the language specified in the request or, if not specified,
    # the automatically-detected language.
    print(f"Language of the text: {response.language_code}")

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