Perform sentiment analysis by using the gcloud tool

Perform sentiment analysis by using the gcloud tool

This page shows you how to get started with the Cloud Natural Language API using the Google Cloud SDK.

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For step-by-step guidance on this task directly in Google Cloud console, click Guide me:

Guide me

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The following sections take you through the same steps as clicking Guide me.

Before you begin

1. Sign in to your Google Cloud account. If you're new to Google Cloud, create an account to evaluate how our products perform in real-world scenarios. New customers also get $300 in free credits to run, test, and deploy workloads.

2. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   Go to project selector

3. Make sure that billing is enabled for your Cloud project. Learn how to check if billing is enabled on a project.

4. Enable the Cloud Natural Language API.

   Enable the API

5. Create a service account:

   1. In the Google Cloud console, go to the Create service account page.

      Go to Create service account
   2. Select your project.

   3. In the Service account name field, enter a name. The Google Cloud console fills in the Service account ID field based on this name.

      In the Service account description field, enter a description. For example, Service account for quickstart.

   4. Click Create and continue.

   5. Click Done to finish creating the service account.

      Do not close your browser window. You will use it in the next step.

6. Create a service account key:

   1. In the Google Cloud console, click the email address for the service account that you created.
   2. Click Keys.
   3. Click Add key, and then click Create new key.
   4. Click Create. A JSON key file is downloaded to your computer.
   5. Click Close.

7. Set the environment variable GOOGLE_APPLICATION_CREDENTIALS to the path of the JSON file that contains your service account key. This variable only applies to your current shell session, so if you open a new session, set the variable again.

   Example: Linux or macOS

   export GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

   Replace KEY_PATH with the path of the JSON file that contains your service account key.

   For example:

   export GOOGLE_APPLICATION_CREDENTIALS="/home/user/Downloads/service-account-file.json"

   Example: Windows

   For PowerShell:

   $env:GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

   Replace KEY_PATH with the path of the JSON file that contains your service account key.

   For example:

   $env:GOOGLE_APPLICATION_CREDENTIALS="C:\Users\username\Downloads\service-account-file.json"

   For command prompt:

   set GOOGLE_APPLICATION_CREDENTIALS=KEY_PATH

   Replace KEY_PATH with the path of the JSON file that contains your service account key.

8. Install and initialize the Google Cloud CLI.

9. In the Google Cloud console, on the project selector page, select or create a Google Cloud project.

   Note: If you don't plan to keep the resources that you create in this procedure, create a project instead of selecting an existing project. After you finish these steps, you can delete the project, removing all resources associated with the project.

   Go to project selector

10. Make sure that billing is enabled for your Cloud project. Learn how to check if billing is enabled on a project.

11. Enable the Cloud Natural Language API.

    Enable the API

12. Create a service account:

    1. In the Google Cloud console, go to the Create service account page.

       Go to Create service account
    2. Select your project.

    3. In the Service account name field, enter a name. The Google Cloud console fills in the Service account ID field based on this name.

       In the Service account description field, enter a description. For example, Service account for quickstart.

    4. Click Create and continue.

    5. Click Done to finish creating the service account.

       Do not close your browser window. You will use it in the next step.

13. Create a service account key:

    1. In the Google Cloud console, click the email address for the service account that you created.
    2. Click Keys.
    3. Click Add key, and then click Create new key.
    4. Click Create. A JSON key file is downloaded to your computer.
    5. Click Close.

14. Set the environment variable GOOGLE_APPLICATION_CREDENTIALS to the path of the JSON file that contains your service account key. This variable only applies to your current shell session, so if you open a new session, set the variable again.

    Example: Linux or macOS

    export GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

    Replace KEY_PATH with the path of the JSON file that contains your service account key.

    For example:

    export GOOGLE_APPLICATION_CREDENTIALS="/home/user/Downloads/service-account-file.json"

    Example: Windows

    For PowerShell:

    $env:GOOGLE_APPLICATION_CREDENTIALS="KEY_PATH"

    Replace KEY_PATH with the path of the JSON file that contains your service account key.

    For example:

    $env:GOOGLE_APPLICATION_CREDENTIALS="C:\Users\username\Downloads\service-account-file.json"

    For command prompt:

    set GOOGLE_APPLICATION_CREDENTIALS=KEY_PATH

    Replace KEY_PATH with the path of the JSON file that contains your service account key.

15. Install and initialize the Google Cloud CLI.

Make an entity analysis request

gcloud

Use the gcloud command line tool to call the analyze-entities command and use the --content flag to specify the text to analyze.

gcloud ml language analyze-entities --content="Michelangelo Caravaggio, Italian painter, is known for 'The Calling of Saint Matthew'."

Command-line

Use curl to make a POST request to the documents:analyzeEntities 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 the service account that you created when you set up the project.

curl -X POST \
  -H "Authorization: Bearer "$(gcloud auth application-default print-access-token) \
  -H "Content-Type: application/json; charset=utf-8" \
 "https://language.googleapis.com/v1/documents:analyzeEntities" \
  --data "{
  'document':{
    'type':'PLAIN_TEXT',
    'content':'Michelangelo Caravaggio, Italian painter, is known for
              \'The Calling of Saint Matthew\'.'
  },
  'encodingType':'UTF8'
}"

You should see a response similar to the following:

{
  "entities": [
    {
      "name": "Michelangelo Caravaggio",
      "type": "PERSON",
      "metadata": {
        "wikipedia_url": "http://en.wikipedia.org/wiki/Caravaggio",
        "mid": "/m/020bg"
      },
      "salience": 0.83047235,
      "mentions": [
        {
          "text": {
            "content": "Michelangelo Caravaggio",
            "beginOffset": 0
          },
          "type": "PROPER"
        },
        {
          "text": {
            "content": "painter",
            "beginOffset": 33
          },
          "type": "COMMON"
        }
      ]
    },
    {
      "name": "Italian",
      "type": "LOCATION",
      "metadata": {
        "mid": "/m/03rjj",
        "wikipedia_url": "http://en.wikipedia.org/wiki/Italy"
      },
      "salience": 0.13870546,
      "mentions": [
        {
          "text": {
            "content": "Italian",
            "beginOffset": 25
          },
          "type": "PROPER"
        }
      ]
    },
    {
      "name": "The Calling of Saint Matthew",
      "type": "EVENT",
      "metadata": {
        "mid": "/m/085_p7",
        "wikipedia_url": "http://en.wikipedia.org/wiki/The_Calling_of_St_Matthew_(Caravaggio)"
      },
      "salience": 0.030822212,
      "mentions": [
        {
          "text": {
            "content": "The Calling of Saint Matthew",
            "beginOffset": 69
          },
          "type": "PROPER"
        }
      ]
    }
  ],
  "language": "en"
}

You can also analyze document sentiment and extract syntax annotations from text by making requests to different Cloud Natural Language API endpoints. See the Cloud Natural Language API Basics for more details.

Clean up

Caution: Deleting a project has the following effects:

• Everything in the project is deleted. If you used an existing project for this tutorial, when you delete it, you also delete any other work you've done in the project.
• Custom project IDs are lost. When you created this project, you might have created a custom project ID that you want to use in the future. To preserve the URLs that use the project ID, such as an appspot.com URL, delete selected resources inside the project instead of deleting the whole project.

If you plan to explore multiple tutorials and quickstarts, reusing projects can help you avoid exceeding project quota limits.

1. In the Google Cloud console, go to the Manage resources page.

   Go to Manage resources

2. In the project list, select the project that you want to delete, and then click Delete.
3. In the dialog, type the project ID, and then click Shut down to delete the project.

What's next

• Get started with the Natural Language API in your language of choice by using a Cloud Natural Language Client Library.

• Consult the Natural Language Basics for conceptual information on forming Natural Language API requests and handling responses.

• Try the Sentiment Analysis Tutorial and browse the Sample Applications.