Language detection guide for Python

The MediaPipe Language Detector task lets you identify the language of a piece of text. These instructions show you how to use the Language Detector with Python. The code sample described in these instructions is available on GitHub.

You can see this task in action by viewing the demo. For more information about the capabilities, models, and configuration options of this task, see the Overview.

Code example

The example code for Language Detector provides a complete implementation of this task in Python for your reference. This code helps you test this task and get started on building your own language detection feature. You can view, run, and edit the Language Detector example code using just your web browser.


This section describes key steps for setting up your development environment and code projects specifically to use Language Detector. For general information on setting up your development environment for using MediaPipe tasks, including platform version requirements, see the Setup guide for Python.


Language Detector uses the mediapipe pip package. You can install the dependency with the following:

$ python -m pip install mediapipe


Import the following classes to access the Language Detector task functions:

import mediapipe as mp
from mediapipe.tasks import python
from mediapipe.tasks.python import text


The MediaPipe Language Detector task requires a trained model that is compatible with this task. For more information on available trained models for Language Detector, see the task overview Models section.

Select and download the model, and then store it within your project directory:

model_path = '/absolute/path/to/language_detector.tflite'

Specify the path of the model with the BaseOptions object model_asset_path parameter, as shown below:

base_options = BaseOptions(model_asset_path=model_path)

Create the task

The MediaPipe Language Detector task uses the create_from_options function to set up the task. The create_from_options function accepts values for configuration options to set the detector options. You can also initialize the task using the create_from_model_path factory function. The create_from_model_path function accepts a relative or absolute path to the trained model file. For more information on configuring tasks, see Configuration options.

The following code demonstrates how to build and configure this task.

base_options = python.BaseOptions(model_asset_path=model_path)
options = text.LanguageDetectorOptions(base_options=base_options)

Configuration options

This task has the following configuration options for Python applications:

Option Name Description Value Range Default Value
max_results Sets the optional maximum number of top-scored language predictions to return. If this value is less than zero, all available results are returned. Any positive numbers -1
score_threshold Sets the prediction score threshold that overrides the one provided in the model metadata (if any). Results below this value are rejected. Any float Not set
category_allowlist Sets the optional list of allowed language codes. If non-empty, language predictions whose language code is not in this set will be filtered out. This option is mutually exclusive with category_denylist and using both results in an error. Any strings Not set
category_denylist Sets the optional list of language codes that are not allowed. If non-empty, language predictions whose language code is in this set will be filtered out. This option is mutually exclusive with category_allowlist and using both results in an error. Any strings Not set

Prepare data

Language Detector works with text (str) data. The task handles the data input preprocessing, including tokenization and tensor preprocessing. All preprocessing is handled within the detect function. There is no need for additional preprocessing of the input text beforehand.

input_text = 'The input text to be classified.'

Run the task

The Language Detector uses the detect function to trigger inferences. For language detection, this means returning the possible languages for the input text.

The following code demonstrates how to execute the processing with the task model.

with python.text.LanguageDetector.create_from_options(options) as detector:
  detection_result = detector.detect(input_text)

Handle and display results

The Language Detector outputs a LanguageDetectorResult consisting of a list of language predictions along with the probabilities for those predictions. The following shows an example of the output data from this task:

  LanguagePrediction #0:
    language_code: "fr"
    probability: 0.999781

This result has been obtained by running the model on the input text: "Il y a beaucoup de bouches qui parlent et fort peu de têtes qui pensent.".

For an example of the code required to process and visualize the results of this task, see the Python sample app.