Analyzing Syntax

While most Natural Language methods analyze what a given text is about, the analyzeSyntax method inspects the structure of the language itself. Syntactic Analysis breaks up the given text into a series of sentences and tokens (generally, words) and provides linguistic information about those tokens. See Morphology & Dependency Trees for details about the linguistic analysis and Language Support for a list of the languages whose syntax the Natural Language API can analyze.

This section demonstrates a few ways to detect syntax in a document. For each document, you must submit a separate request.

Analyzing Syntax in a String

Here is an example of performing syntactic analysis on a text string sent directly to the Natural Language API:

Protocol

To analyze syntax in a document, make a POST request to the documents:analyzeSyntax REST method and provide the appropriate request body as shown in the following example.

The example uses the gcloud auth application-default print-access-token command to obtain an access token for a service account set up for the project using the Google Cloud Platform gcloud CLI. For instructions on installing the gcloud CLI, setting up a project with a service account see the Quickstart.

curl -X POST \
     -H "Authorization: Bearer "$(gcloud auth application-default print-access-token) \
     -H "Content-Type: application/json; charset=utf-8" \
     --data "{
  'encodingType': 'UTF8',
  'document': {
    'type': 'PLAIN_TEXT',
    'content': 'Google, headquartered in Mountain View, unveiled the new Android phone at the Consumer Electronic Show.  Sundar Pichai said in his keynote that users love their new Android phones.'
  }
}" "https://language.googleapis.com/v1/documents:analyzeSyntax"

If you don't specify document.language, then the language will be automatically detected. For information on which languages are supported by the Natural Language API, see Language Support. See the Document reference documentation for more information on configuring the request body.

If the request is successful, the server returns a 200 OK HTTP status code and the response in JSON format:

{
  "sentences": [
    {
      "text": {
        "content": "Google, headquartered in Mountain View, unveiled the new Android phone at the Consumer Electronic Show.",
        "beginOffset": 0
      }
    },
    {
      "text": {
        "content": "Sundar Pichai said in his keynote that users love their new Android phones.",
        "beginOffset": 105
      }
    }
  ],
  "tokens": [
    {
      "text": {
        "content": "Google",
        "beginOffset": 0
      },
      "partOfSpeech": {
        "tag": "NOUN",
        "aspect": "ASPECT_UNKNOWN",
        "case": "CASE_UNKNOWN",
        "form": "FORM_UNKNOWN",
        "gender": "GENDER_UNKNOWN",
        "mood": "MOOD_UNKNOWN",
        "number": "SINGULAR",
        "person": "PERSON_UNKNOWN",
        "proper": "PROPER",
        "reciprocity": "RECIPROCITY_UNKNOWN",
        "tense": "TENSE_UNKNOWN",
        "voice": "VOICE_UNKNOWN"
      },
      "dependencyEdge": {
        "headTokenIndex": 7,
        "label": "NSUBJ"
      },
      "lemma": "Google"
    },
    ...
    {
      "text": {
        "content": ".",
        "beginOffset": 179
      },
      "partOfSpeech": {
        "tag": "PUNCT",
        "aspect": "ASPECT_UNKNOWN",
        "case": "CASE_UNKNOWN",
        "form": "FORM_UNKNOWN",
        "gender": "GENDER_UNKNOWN",
        "mood": "MOOD_UNKNOWN",
        "number": "NUMBER_UNKNOWN",
        "person": "PERSON_UNKNOWN",
        "proper": "PROPER_UNKNOWN",
        "reciprocity": "RECIPROCITY_UNKNOWN",
        "tense": "TENSE_UNKNOWN",
        "voice": "VOICE_UNKNOWN"
      },
      "dependencyEdge": {
        "headTokenIndex": 20,
        "label": "P"
      },
      "lemma": "."
    }
  ],
  "language": "en"
}

The tokens array contains Token objects representing the detected sentence tokens, which include information such as a token's part of speech and its position in the sentence.

gcloud

Refer to the analyze-syntax command for complete details.

To perform syntax analysis, use the gcloud CLI and use the --content flag to identify the content to analyze:

gcloud ml language analyze-syntax --content="Google, headquartered in Mountain View, unveiled the new Android phone at the Consumer Electronic Show.  Sundar Pichai said in his keynote that users love their new Android phones."

If the request is successful, the server returns a response in JSON format:

{
  "sentences": [
    {
      "text": {
        "content": "Google, headquartered in Mountain View, unveiled the new Android phone at the Consumer Electronic Show.",
        "beginOffset": 0
      }
    },
    {
      "text": {
        "content": "Sundar Pichai said in his keynote that users love their new Android phones.",
        "beginOffset": 105
      }
    }
  ],
  "tokens": [
    {
      "text": {
        "content": "Google",
        "beginOffset": 0
      },
      "partOfSpeech": {
        "tag": "NOUN",
        "aspect": "ASPECT_UNKNOWN",
        "case": "CASE_UNKNOWN",
        "form": "FORM_UNKNOWN",
        "gender": "GENDER_UNKNOWN",
        "mood": "MOOD_UNKNOWN",
        "number": "SINGULAR",
        "person": "PERSON_UNKNOWN",
        "proper": "PROPER",
        "reciprocity": "RECIPROCITY_UNKNOWN",
        "tense": "TENSE_UNKNOWN",
        "voice": "VOICE_UNKNOWN"
      },
      "dependencyEdge": {
        "headTokenIndex": 7,
        "label": "NSUBJ"
      },
      "lemma": "Google"
    },
    ...
    {
      "text": {
        "content": ".",
        "beginOffset": 179
      },
      "partOfSpeech": {
        "tag": "PUNCT",
        "aspect": "ASPECT_UNKNOWN",
        "case": "CASE_UNKNOWN",
        "form": "FORM_UNKNOWN",
        "gender": "GENDER_UNKNOWN",
        "mood": "MOOD_UNKNOWN",
        "number": "NUMBER_UNKNOWN",
        "person": "PERSON_UNKNOWN",
        "proper": "PROPER_UNKNOWN",
        "reciprocity": "RECIPROCITY_UNKNOWN",
        "tense": "TENSE_UNKNOWN",
        "voice": "VOICE_UNKNOWN"
      },
      "dependencyEdge": {
        "headTokenIndex": 20,
        "label": "P"
      },
      "lemma": "."
    }
  ],
  "language": "en"
}

The tokens array contains Token objects representing the detected sentence tokens, which include information such as a token's part of speech and its position in the sentence.

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.


func analyzeSyntax(ctx context.Context, client *language.Client, text string) (*languagepb.AnnotateTextResponse, error) {
	return client.AnnotateText(ctx, &languagepb.AnnotateTextRequest{
		Document: &languagepb.Document{
			Source: &languagepb.Document_Content{
				Content: text,
			},
			Type: languagepb.Document_PLAIN_TEXT,
		},
		Features: &languagepb.AnnotateTextRequest_Features{
			ExtractSyntax: true,
		},
		EncodingType: languagepb.EncodingType_UTF8,
	})
}

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.

// Instantiate the Language client com.google.cloud.language.v1.LanguageServiceClient
try (com.google.cloud.language.v1.LanguageServiceClient language =
    com.google.cloud.language.v1.LanguageServiceClient.create()) {
  com.google.cloud.language.v1.Document