fast-langdetect 🚀

Overview

fast-langdetect provides ultra-fast and highly accurate language detection based on FastText, a library developed by Facebook. This package is 80x faster than traditional methods and offers 95% accuracy.

It supports Python versions 3.9 to 3.12.

Support offline usage.

This project builds upon zafercavdar/fasttext-langdetect with enhancements in packaging.

For more information on the underlying FastText model, refer to the official documentation: FastText Language Identification.

Note

This library requires over 200MB of memory to use in low memory mode.

Installation 💻

To install fast-langdetect, you can use either pip or pdm:

Using pip

pip install fast-langdetect

Using pdm

pdm add fast-langdetect

Usage 🖥️

For optimal performance and accuracy in language detection, use detect(text, low_memory=False) to load the larger model.

The model will be downloaded to the /tmp/fasttext-langdetect directory upon first use.

Native API (Recommended)

Note

This function assumes to be given a single line of text. You should remove \n characters before passing the text. If the sample is too long or too short, the accuracy will decrease (for example, in the case of too short, Chinese will be predicted as Japanese).

from fast_langdetect import detect, detect_multilingual

# Single language detection
print(detect("Hello, world!"))
# Output: {'lang': 'en', 'score': 0.12450417876243591}

# `use_strict_mode` determines whether the model loading process should enforce strict conditions before using fallback options.
# If `use_strict_mode` is set to True, we will load only the selected model, not the fallback model.
print(detect("Hello, world!", low_memory=False, use_strict_mode=True))

# How to deal with multiline text
multiline_text = """
Hello, world!
This is a multiline text.
But we need remove `\n` characters or it will raise an ValueError.
"""
multiline_text = multiline_text.replace("\n", "")  # NOTE:ITS IMPORTANT TO REMOVE \n CHARACTERS
print(detect(multiline_text))
# Output: {'lang': 'en', 'score': 0.8509423136711121}

print(detect("Привет, мир!")["lang"])
# Output: ru

# Multi-language detection
print(detect_multilingual("Hello, world!你好世界!Привет, мир!"))
# Output: [{'lang': 'ja', 'score': 0.32009604573249817}, {'lang': 'uk', 'score': 0.27781224250793457}, {'lang': 'zh', 'score': 0.17542070150375366}, {'lang': 'sr', 'score': 0.08751443773508072}, {'lang': 'bg', 'score': 0.05222449079155922}]

# Multi-language detection with low memory mode disabled
print(detect_multilingual("Hello, world!你好世界!Привет, мир!", low_memory=False))
# Output: [{'lang': 'ru', 'score': 0.39008623361587524}, {'lang': 'zh', 'score': 0.18235979974269867}, {'lang': 'ja', 'score': 0.08473210036754608}, {'lang': 'sr', 'score': 0.057975586503744125}, {'lang': 'en', 'score': 0.05422825738787651}]

Convenient detect_language Function

from fast_langdetect import detect_language

# Single language detection
print(detect_language("Hello, world!"))
# Output: EN

print(detect_language("Привет, мир!"))
# Output: RU

print(detect_language("你好，世界！"))
# Output: ZH

Splitting Text by Language 🌐

For text splitting based on language, please refer to the split-lang repository.

Benchmark 📊

For detailed benchmark results, refer to zafercavdar/fasttext-langdetect#benchmark.

References 📚

[1] A. Joulin, E. Grave, P. Bojanowski, T. Mikolov, Bag of Tricks for Efficient Text Classification

@article{joulin2016bag,
  title={Bag of Tricks for Efficient Text Classification},
  author={Joulin, Armand and Grave, Edouard and Bojanowski, Piotr and Mikolov, Tomas},
  journal={arXiv preprint arXiv:1607.01759},
  year={2016}
}

[2] A. Joulin, E. Grave, P. Bojanowski, M. Douze, H. Jégou, T. Mikolov, FastText.zip: Compressing text classification models

@article{joulin2016fasttext,
  title={FastText.zip: Compressing text classification models},
  author={Joulin, Armand and Grave, Edouard and Bojanowski, Piotr and Douze, Matthijs and J{\'e}gou, H{\'e}rve and Mikolov, Tomas},
  journal={arXiv preprint arXiv:1612.03651},
  year={2016}
}