Get text embeddings

This document describes how to create a text embedding using the Vertex AI Text embeddings API.

Vertex AI text embeddings API uses dense vector representations: text-embedding-gecko, for example, uses 768-dimensional vectors. Dense vector embedding models use deep-learning methods similar to the ones used by large language models. Unlike sparse vectors, which tend to directly map words to numbers, dense vectors are designed to better represent the meaning of a piece of text. The benefit of using dense vector embeddings in generative AI is that instead of searching for direct word or syntax matches, you can better search for passages that align to the meaning of the query, even if the passages don't use the same language.

The vectors are normalized, so you can use cosine similarity, dot product, or Euclidean distance to provide the same similarity rankings.

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.

    Go to project selector

  3. Enable the Vertex AI API.

    Enable the API

    4.

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

    Go to project selector

  5. Enable the Vertex AI API.

    Enable the API

    6.
  6. Choose a task type for your embeddings job.

Supported models

You can get text embeddings by using the following models:

English models Multilingual models
textembedding-gecko@001 textembedding-gecko-multilingual@001
textembedding-gecko@002 text-multilingual-embedding-002
textembedding-gecko@003
text-embedding-004
text-embedding-005

If you are new to these models, we recommend that you use the latest versions. For English text, use text-embedding-005. For multilingual text, use text-multilingual-embedding-002.

Get text embeddings for a snippet of text

You can get text embeddings for a snippet of text by using the Vertex AI API or the Vertex AI SDK for Python. For each request, you're limited to 250 input texts in us-central1, and in other regions, the max input text is 5. The API has a maximum input token limit of 20,000. Inputs exceeding this limit results in a 500 error. Each individual input text is further limited to 2048 tokens; any excess is silently truncated. You can also disable silent truncation by setting autoTruncate to false.

All models produce an output with 768 dimensions by default. However, the following models give users the option to choose an output dimensionality between 1 and 768. By selecting a smaller output dimensionality, users can save memory and storage space, leading to more efficient computations.

  • text-embedding-005
  • text-multilingual-embedding-002

The following examples use the text-embedding-005 model.

Gen AI SDK for Python

Learn how to install or update the Google Gen AI SDK for Python.
For more information, see the Gen AI SDK for Python API reference documentation or the python-genai GitHub repository.
Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=us-central1
export GOOGLE_GENAI_USE_VERTEXAI=True
 

from google import genai
from google.genai.types import EmbedContentConfig

client = genai.Client()
response = client.models.embed_content(
    model="text-embedding-005",
    contents=[
        "How do I get a driver's license/learner's permit?",
        "How do I renew my driver's license?",
        "How do I change my address on my driver's license?",
    ],
    config=EmbedContentConfig(
        task_type="RETRIEVAL_DOCUMENT",  # Optional
        output_dimensionality=768,  # Optional
        title="Driver's License",  # Optional
    ),
)
print(response)
# Example response:
# embeddings=[ContentEmbedding(values=[-0.06302902102470398, 0.00928034819662571, 0.014716853387653828, -0.028747491538524628, ... ],
# statistics=ContentEmbeddingStatistics(truncated=False, token_count=13.0))]
# metadata=EmbedContentMetadata(billable_character_count=112)

Vertex AI SDK for Python

To learn how to install or update the Vertex AI SDK for Python, see Install the Vertex AI SDK for Python. For more information, see the Vertex AI SDK for Python API reference documentation. 

from __future__ import annotations

from vertexai.language_models import TextEmbeddingInput, TextEmbeddingModel


def embed_text() -> list[list[float]]:
    """Embeds texts with a pre-trained, foundational model.

    Returns:
        A list of lists containing the embedding vectors for each input text
    """

    # A list of texts to be embedded.
    texts = ["banana muffins? ", "banana bread? banana muffins?"]
    # The dimensionality of the output embeddings.
    dimensionality = 256
    # The task type for embedding. Check the available tasks in the model's documentation.
    task = "RETRIEVAL_DOCUMENT"

    model = TextEmbeddingModel.from_pretrained("text-embedding-005")
    inputs = [TextEmbeddingInput(text, task) for text in texts]
    kwargs = dict(output_dimensionality=dimensionality) if dimensionality else {}
    embeddings = model.get_embeddings(inputs, **kwargs)

    print(embeddings)
    # Example response:
    # [[0.006135190837085247, -0.01462465338408947, 0.004978656303137541, ...], [0.1234434666, ...]],
    return [embedding.values for embedding in embeddings]

Go

Before trying this sample, follow the Go setup instructions in the Vertex AI quickstart using client libraries. For more information, see the Vertex AI Go API reference documentation.

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

import (
	"context"
	"fmt"
	"io"

	aiplatform "cloud.google.com/go/aiplatform/apiv1"
	"cloud.google.com/go/aiplatform/apiv1/aiplatformpb"

	"google.golang.org/api/option"
	"google.golang.org/protobuf/types/known/structpb"
)

// embedTexts shows how embeddings are set for text-embedding-005 model
func embedTexts(w io.Writer, project, location string) error {
	// location := "us-central1"
	ctx := context.Background()

	apiEndpoint := fmt.Sprintf("%s-aiplatform.googleapis.com:443", location)
	dimensionality := 5
	model := "text-embedding-005"
	texts := []string{"banana muffins? ", "banana bread? banana muffins?"}

	client, err := aiplatform.NewPredictionClient(ctx, option.WithEndpoint(apiEndpoint))
	if err != nil {
		return err
	}
	defer client.Close()

	endpoint := fmt.Sprintf("projects/%s/locations/%s/publishers/google/models/%s", project, location, model)
	instances := make([]*structpb.Value, len(texts))
	for i, text := range texts {
		instances[i] = structpb.NewStructValue(&structpb.Struct{
			Fields: map[string]*structpb.Value{
				"content":   structpb.NewStringValue(text),
				"task_type": structpb.NewStringValue("QUESTION_ANSWERING"),
			},
		})
	}

	params := structpb.NewStructValue(&structpb.Struct{
		Fields: map[string]*structpb.Value{
			"outputDimensionality": structpb.NewNumberValue(float64(dimensionality)),
		},
	})

	req := &aiplatformpb.PredictRequest{
		Endpoint:   endpoint,
		Instances:  instances,
		Parameters: params,
	}
	resp, err := client.Predict(ctx, req)
	if err != nil {
		return err
	}
	embeddings := make([][]float32, len(resp.Predictions))
	for i, prediction := range resp.Predictions {
		values := prediction.GetStructValue().Fields["embeddings"].GetStructValue().Fields["values"].GetListValue().Values
		embeddings[i] = make([]float32, len(values))
		for j, value := range values {
			embeddings[i][j] = float32(value.GetNumberValue())
		}
	}

	fmt.Fprintf(w, "Dimensionality: %d. Embeddings length: %d", len(embeddings[0]), len(embeddings))
	return nil
}

Java

Before trying this sample, follow the Java setup instructions in the Vertex AI quickstart using client libraries. For more information, see the Vertex AI Java API reference documentation.

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

import static java.util.stream.Collectors.toList;

import com.google.cloud.aiplatform.v1.EndpointName;
import com.google.cloud.aiplatform.v1.PredictRequest;
import com.google.cloud.aiplatform.v1.PredictResponse;
import com.google.cloud.aiplatform.v1.PredictionServiceClient;
import com.google.cloud.aiplatform.v1.PredictionServiceSettings;
import com.google.protobuf.Struct;
import com.google.protobuf.Value;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.OptionalInt;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class PredictTextEmbeddingsSample {
  public static void main(String[] args) throws IOException {
    // TODO(developer): Replace these variables before running the sample.
    // Details about text embedding request structure and supported models are available in:
    // https://cloud.google.com/vertex-ai/docs/generative-ai/embeddings/get-text-embeddings
    String endpoint = "us-central1-aiplatform.googleapis.com:443";
    String project = "YOUR_PROJECT_ID";
    String model = "text-embedding-005";
    predictTextEmbeddings(
        endpoint,
        project,
        model,
        List.of("banana bread?", "banana muffins?"),
        "QUESTION_ANSWERING",
        OptionalInt.of(256));
  }

  // Gets text embeddings from a pretrained, foundational model.
  public static List<List<Float>> predictTextEmbeddings(
      String endpoint,
      String project,
      String model,
      List<String> texts,
      String task,
      OptionalInt outputDimensionality)
      throws IOException {
    PredictionServiceSettings settings =
        PredictionServiceSettings.newBuilder().setEndpoint(endpoint).build();
    Matcher matcher = Pattern.compile("^(?<Location>\\w+-\\w+)").matcher(endpoint);
    String location = matcher.matches() ? matcher.group("Location") : "us-central1";
    EndpointName endpointName =
        EndpointName.ofProjectLocationPublisherModelName(project, location, "google", model);

    // You can use this prediction service client for multiple requests.
    try (PredictionServiceClient client = PredictionServiceClient.create(settings)) {
      PredictRequest.Builder request =
          PredictRequest.newBuilder().setEndpoint(endpointName.toString());
      if (outputDimensionality.isPresent()) {
        request.setParameters(
            Value.newBuilder()
                .setStructValue(
                    Struct.newBuilder()
                        .putFields("outputDimensionality", valueOf(outputDimensionality.getAsInt()))
                        .build()));
      }
      for (int i = 0; i < texts.size(); i++) {
        request.addInstances(
            Value.newBuilder()
                .setStructValue(
                    Struct.newBuilder()
                        .putFields("content", valueOf(texts.get(i)))
                        .putFields("task_type", valueOf(task))
                        .build()));
      }
      PredictResponse response = client.predict(request.build());
      List<List<Float>> floats = new ArrayList<>();
      for (Value prediction : response.getPredictionsList()) {
        Value embeddings = prediction.getStructValue().getFieldsOrThrow("embeddings");
        Value values = embeddings.getStructValue().getFieldsOrThrow("values");
        floats.add(
            values.getListValue().getValuesList().stream()
                .map(Value::getNumberValue)
                .map(Double::floatValue)
                .collect(toList()));
      }
      return floats;
    }
  }

  private static Value valueOf(String s) {
    return Value.newBuilder().setStringValue(s).build();
  }

  private static Value valueOf(int n) {
    return Value.newBuilder().setNumberValue(n).build();
  }
}

Node.js

Before trying this sample, follow the Node.js setup instructions in the Vertex AI quickstart using client libraries. For more information, see the Vertex AI Node.js API reference documentation.

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

async function main(
  project,
  model = 'text-embedding-005',
  texts = 'banana bread?;banana muffins?',
  task = 'QUESTION_ANSWERING',
  dimensionality = 0,
  apiEndpoint = 'us-central1-aiplatform.googleapis.com'
) {
  const aiplatform = require('@google-cloud/aiplatform');
  const {PredictionServiceClient} = aiplatform.v1;
  const {helpers} = aiplatform; // helps construct protobuf.Value objects.
  const clientOptions = {apiEndpoint: apiEndpoint};
  const location = 'us-central1';
  const endpoint = `projects/${project}/locations/${location}/publishers/google/models/${model}`;

  async function callPredict() {
    const instances = texts
      .split(';')
      .map(e => helpers.toValue({content: e, task_type: task}));
    const parameters = helpers.toValue(
      dimensionality > 0 ? {outputDimensionality: parseInt(dimensionality)} : {}
    );
    const request = {endpoint, instances, parameters};
    const client = new PredictionServiceClient(clientOptions);
    const [response] = await client.predict(request);
    const predictions = response.predictions;
    const embeddings = predictions.map(p => {
      const embeddingsProto = p.structValue.fields.embeddings;
      const valuesProto = embeddingsProto.structValue.fields.values;
      return valuesProto.listValue.values.map(v => v.numberValue);
    });
    console.log('Got embeddings: \n' + JSON.stringify(embeddings));
  }

  callPredict();
}

Add an embedding to a vector database

After you've generated your embedding you can add embeddings to a vector database, like Vector Search. This enables low-latency retrieval, and is critical as the size of your data increases.

To learn more about Vector Search, see Overview of Vector Search.

What's next