GPT3Tokenizer for PHP

This package is forked from https://packagist.org/packages/gioni06/gpt3-tokenizer and changed to support php 7, thanks to the original author!

This is a PHP port of the GPT-3 tokenizer. It is based on the original Python implementation and the Nodejs implementation.

GPT-2 and GPT-3 use a technique called byte pair encoding to convert text into a sequence of integers, which are then used as input for the model. When you interact with the OpenAI API, you may find it useful to calculate the amount of tokens in a given text before sending it to the API.

If you want to learn more, read the Summary of the tokenizers from Hugging Face.

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Installation

Install the package from Packagist using Composer:

composer require everstu/gpt3-tokenizer

Testing

Loading the vocabulary files consumes a lot of memory. You might need to increase the phpunit memory limit. https://stackoverflow.com/questions/46448294/phpunit-coverage-allowed-memory-size-of-536870912-bytes-exhausted

./vendor/bin/phpunit -d memory_limit=-1 tests/

Use the configuration Class

use everstu\Gpt3Tokenizer\Gpt3TokenizerConfig;

// default vocab path
// default merges path
// caching enabled
$defaultConfig = new Gpt3TokenizerConfig();

$customConfig = new Gpt3TokenizerConfig();
$customConfig
    ->vocabPath('custom_vocab.json') // path to a custom vocabulary file
    ->mergesPath('custom_merges.txt') // path to a custom merges file
    ->useCache(false)

A note on caching

The tokenizer will try to use apcu for caching, if that is not available it will use a plain PHP array. You will see slightly better performance for long texts when using the cache. The cache is enabled by default.

Encode a text

use everstu\Gpt3Tokenizer\Gpt3TokenizerConfig;
use everstu\Gpt3Tokenizer\Gpt3Tokenizer;

$config = new Gpt3TokenizerConfig();
$tokenizer = new Gpt3Tokenizer($config);
$text = "This is some text";
$tokens = $tokenizer->encode($text);
// [1212,318,617,2420]

Decode a text

use everstu\Gpt3Tokenizer\Gpt3TokenizerConfig;
use everstu\Gpt3Tokenizer\Gpt3Tokenizer;

$config = new Gpt3TokenizerConfig();
$tokenizer = new Gpt3Tokenizer($config);
$tokens = [1212,318,617,2420]
$text = $tokenizer->decode($tokens);
// "This is some text"

Count the number of tokens in a text

use everstu\Gpt3Tokenizer\Gpt3TokenizerConfig;
use everstu\Gpt3Tokenizer\Gpt3Tokenizer;

$config = new Gpt3TokenizerConfig();
$tokenizer = new Gpt3Tokenizer($config);
$text = "This is some text";
$numberOfTokens = $tokenizer->count($text);
// 4

License

This project uses the Apache License 2.0 license. See the LICENSE file for more information.