{ "cells": [ { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "# How to count tokens with tiktoken\n", "\n", "[`tiktoken`](https://github.com/openai/tiktoken/blob/main/README.md) is a fast open-source tokenizer by OpenAI.\n", "\n", "Given a text string (e.g., `\"tiktoken is great!\"`) and an encoding (e.g., `\"gpt2\"`), a tokenizer can split the text string into a list of tokens (e.g., `[\"t\", \"ik\", \"token\", \" is\", \" great\", \"!\"]`).\n", "\n", "Splitting text strings into tokens is useful because models like GPT-3 see text in the form of tokens. Knowing how many tokens are in a text string can tell you (a) whether the string is too long for a text model to process and (b) how much an OpenAI API call costs (as usage is priced by token). Different models use different encodings.\n", "\n", "`tiktoken` supports three encodings used by OpenAI models:\n", "\n", "| Encoding name | OpenAI models |\n", "|-------------------------|-----------------------------------------------------|\n", "| `gpt2` (or `r50k_base`) | Most GPT-3 models |\n", "| `p50k_base` | Code models, `text-davinci-002`, `text-davinci-003` |\n", "| `cl100k_base` | `text-embedding-ada-002` |\n", "\n", "`p50k_base` overlaps substantially with `gpt2`, and for non-code applications, they will usually give the same tokens.\n", "\n", "## Tokenizer libraries and languages\n", "\n", "For `gpt2` encodings, tokenizers are available in many languages.\n", "- Python: [tiktoken](https://github.com/openai/tiktoken/blob/main/README.md) (or alternatively [GPT2TokenizerFast](https://huggingface.co/docs/transformers/model_doc/gpt2#transformers.GPT2TokenizerFast))\n", "- JavaScript: [gpt-3-encoder](https://www.npmjs.com/package/gpt-3-encoder)\n", "- .NET / C#: [GPT Tokenizer](https://github.com/dluc/openai-tools)\n", "- Java: [gpt2-tokenizer-java](https://github.com/hyunwoongko/gpt2-tokenizer-java)\n", "- PHP: [GPT-3-Encoder-PHP](https://github.com/CodeRevolutionPlugins/GPT-3-Encoder-PHP)\n", "\n", "(OpenAI makes no endorsements or guarantees of third-party libraries.)\n", "\n", "For `p50k_base` and `cl100k_base` encodings, `tiktoken` is the only tokenizer available as of January 2023.\n", "- Python: [tiktoken](https://github.com/openai/tiktoken/blob/main/README.md)\n", "\n", "## How strings are typically tokenized\n", "\n", "In English, tokens commonly range in length from one character to one word (e.g., `\"t\"` or `\" great\"`), though in some languages tokens can be shorter than one character or longer than one word. Spaces are usually grouped with the starts of words (e.g., `\" is\"` instead of `\"is \"` or `\" \"`+`\"is\"`). You can quickly check how a string is tokenized at the [OpenAI Tokenizer](https://beta.openai.com/tokenizer)." ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 0. Install `tiktoken`\n", "\n", "In your terminal, install `tiktoken` with `pip`:\n", "\n", "```bash\n", "pip install tiktoken\n", "```" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 1. Import `tiktoken`" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "from typing import Iterable, Sequence, Optional\n", "\n", "import tiktoken\n" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 2. Load an encoding\n", "\n", "Use `tiktoken.get_encoding()` to load an encoding by name.\n", "\n", "The first time this runs, it will require an internet connection to download. Later runs won't need an internet connection." ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "encoding = tiktoken.get_encoding(\"cl100k_base\")\n" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 3. Turn text into tokens with `encoding.encode()`\n", "\n" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "The `.encode()` method converts a text string into a list of token integers." ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "encoding.encode(\"tiktoken is great!\")\n" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "Count tokens by counting the length of the list returned by `.encode()`." ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "def num_tokens_from_string(string: str, encoding_name: str) -> int:\n", " \"\"\"Returns the number of tokens in a text string.\"\"\"\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " num_tokens = len(encoding.encode(string))\n", " return num_tokens\n" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "num_tokens_from_string(\"tiktoken is great!\", \"gpt2\")\n" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 4. Turn tokens into text with `encoding.decode()`" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "`.decode()` converts a list of token integers to a string." ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "encoding.decode([83, 1134, 30001, 318, 1049, 0])\n" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "Warning: although `.decode()` can be applied to single tokens, beware that it can be lossy for tokens that aren't on utf-8 boundaries." ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "For single tokens, `.decode_single_token_bytes()` safely converts a single integer token to the bytes it represents." ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "[encoding.decode_single_token_bytes(token) for token in [83, 1134, 30001, 318, 1049, 0]]\n" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "(The `b` in front of the strings indicates that the strings are byte strings.)" ] }, { "attachments": {}, "cell_type": "markdown", "metadata": {}, "source": [ "## 5. Comparing encodings\n", "\n", "Different encodings can vary in how they split words, group spaces, and handle non-English characters. Using the methods above, we can compare different encodings on a few example strings." ] }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "def compare_encodings(example_string: str) -> None:\n", " \"\"\"Prints a comparison of three string encodings.\"\"\"\n", " # print the example string\n", " print(f'\\nExample string: \"{example_string}\"')\n", " # for each encoding, print the # of tokens, the token integers, and the token bytes\n", " for encoding_name in [\"gpt2\", \"p50k_base\", \"cl100k_base\"]:\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " token_integers = encoding.encode(example_string)\n", " num_tokens = len(token_integers)\n", " token_bytes = [encoding.decode_single_token_bytes(token) for token in token_integers]\n", " print()\n", " print(f\"{encoding_name}: {num_tokens} tokens\")\n", " print(f\"token integers: {token_integers}\")\n", " print(f\"token bytes: {token_bytes}\")#%% md\n", "# How to count tokens with tiktoken\n", "\n", "[`tiktoken`](https://github.com/openai/tiktoken/blob/main/README.md) is a fast open-source tokenizer by OpenAI.\n", "\n", "Given a text string (e.g., `\"tiktoken is great!\"`) and an encoding (e.g., `\"gpt2\"`), a tokenizer can split the text string into a list of tokens (e.g., `[\"t\", \"ik\", \"token\", \" is\", \" great\", \"!\"]`).\n", "\n", "Splitting text strings into tokens is useful because models like GPT-3 see text in the form of tokens. Knowing how many tokens are in a text string can tell you (a) whether the string is too long for a text model to process and (b) how much an OpenAI API call costs (as usage is priced by token). Different models use different encodings.\n", "\n", "`tiktoken` supports three encodings used by OpenAI models:\n", "\n", "| Encoding name | OpenAI models |\n", "|-------------------------|-----------------------------------------------------|\n", "| `gpt2` (or `r50k_base`) | Most GPT-3 models |\n", "| `p50k_base` | Code models, `text-davinci-002`, `text-davinci-003` |\n", "| `cl100k_base` | `text-embedding-ada-002` |\n", "\n", "`p50k_base` overlaps substantially with `gpt2`, and for non-code applications, they will usually give the same tokens.\n", "\n", "## Tokenizer libraries and languages\n", "\n", "For `gpt2` encodings, tokenizers are available in many languages.\n", "- Python: [tiktoken](https://github.com/openai/tiktoken/blob/main/README.md) (or alternatively [GPT2TokenizerFast](https://huggingface.co/docs/transformers/model_doc/gpt2#transformers.GPT2TokenizerFast))\n", "- JavaScript: [gpt-3-encoder](https://www.npmjs.com/package/gpt-3-encoder)\n", "- .NET / C#: [GPT Tokenizer](https://github.com/dluc/openai-tools)\n", "- Java: [gpt2-tokenizer-java](https://github.com/hyunwoongko/gpt2-tokenizer-java)\n", "- PHP: [GPT-3-Encoder-PHP](https://github.com/CodeRevolutionPlugins/GPT-3-Encoder-PHP)\n", "\n", "(OpenAI makes no endorsements or guarantees of third-party libraries.)\n", "\n", "For `p50k_base` and `cl100k_base` encodings, `tiktoken` is the only tokenizer available as of January 2023.\n", "- Python: [tiktoken](https://github.com/openai/tiktoken/blob/main/README.md)\n", "\n", "## How strings are typically tokenized\n", "\n", "In English, tokens commonly range in length from one character to one word (e.g., `\"t\"` or `\" great\"`), though in some languages tokens can be shorter than one character or longer than one word. Spaces are usually grouped with the starts of words (e.g., `\" is\"` instead of `\"is \"` or `\" \"`+`\"is\"`). You can quickly check how a string is tokenized at the [OpenAI Tokenizer](https://beta.openai.com/tokenizer)." ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "## 0. Install `tiktoken`\n", "\n", "In your terminal, install `tiktoken` with `pip`:\n", "\n", "```bash\n", "pip install tiktoken\n", "```" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "## 1. Import `tiktoken`" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "from typing import Iterable, Sequence, Optional\n", "\n", "import tiktoken\n" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "## 2. Load an encoding\n", "\n", "Use `tiktoken.get_encoding()` to load an encoding by name.\n", "\n", "The first time this runs, it will require an internet connection to download. Later runs won't need an internet connection." ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "encoding = tiktoken.get_encoding(\"cl100k_base\")\n" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "## 3. Turn text into tokens with `encoding.encode()`\n", "\n" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "The `.encode()` method converts a text string into a list of token integers." ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "encoding.encode(\"tiktoken is great!\")\n" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "Count tokens by counting the length of the list returned by `.encode()`." ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "def num_tokens_from_string(string: str, encoding_name: str) -> int:\n", " \"\"\"Returns the number of tokens in a text string.\"\"\"\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " num_tokens = len(encoding.encode(string))\n", " return num_tokens\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "num_tokens_from_string(\"tiktoken is great!\", \"gpt2\")\n" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "## 4. Turn tokens into text with `encoding.decode()`" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "`.decode()` converts a list of token integers to a string." ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "encoding.decode([83, 1134, 30001, 318, 1049, 0])\n" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "Warning: although `.decode()` can be applied to single tokens, beware that it can be lossy for tokens that aren't on utf-8 boundaries." ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "For single tokens, `.decode_single_token_bytes()` safely converts a single integer token to the bytes it represents." ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "[encoding.decode_single_token_bytes(token) for token in [83, 1134, 30001, 318, 1049, 0]]\n" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "(The `b` in front of the strings indicates that the strings are byte strings.)" ], "metadata": { "collapsed": false } }, { "cell_type": "markdown", "source": [ "## 5. Comparing encodings\n", "\n", "Different encodings can vary in how they split words, group spaces, and handle non-English characters. Using the methods above, we can compare different encodings on a few example strings." ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "def compare_encodings(example_string: str) -> None:\n", " \"\"\"Prints a comparison of three string encodings.\"\"\"\n", " # print the example string\n", " print(f'\\nExample string: \"{example_string}\"')\n", " # for each encoding, print the # of tokens, the token integers, and the token bytes\n", " for encoding_name in [\"gpt2\", \"p50k_base\", \"cl100k_base\"]:\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " token_integers = encoding.encode(example_string)\n", " num_tokens = len(token_integers)\n", " token_bytes = [encoding.decode_single_token_bytes(token) for token in token_integers]\n", " print()\n", " print(f\"{encoding_name}: {num_tokens} tokens\")\n", " print(f\"token integers: {token_integers}\")\n", " print(f\"token bytes: {token_bytes}\")\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "compare_encodings(\"antidisestablishmentarianism\")\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "compare_encodings(\"2 + 2 = 4\")\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "compare_encodings(\"お誕生日おめでとう\")\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "long_prompt = str(list(range(3000)))\n", "num_tokens_from_string(long_prompt, 'cl100k_base')" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "import openai\n", "EMBEDDING_MODEL = 'text-embedding-ada-002'\n", "EMBEDDING_CTX_LENGTH = 8191\n", "openai.Embedding.create(input=long_prompt, model=EMBEDDING_MODEL)\n", "\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "def truncate_string_tokens(text: str, encoding_name: str = 'cl100k_base', max_tokens: int = EMBEDDING_CTX_LENGTH) -> list[int]:\n", " \"\"\"Truncate a string to have `max_tokens` according to the given encoding.\"\"\"\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " return encoding.encode(text)[:max_tokens]\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "from itertools import islice\n", "\n", "# From: https://docs.python.org/3/library/itertools.html#itertools-recipes\n", "def batched(iterable, n):\n", " \"\"\"Batch data into tuples of length n. The last batch may be shorter.\"\"\"\n", " # batched('ABCDEFG', 3) --> ABC DEF G\n", " if n < 1:\n", " raise ValueError('n must be at least one')\n", " it = iter(iterable)\n", " while (batch := tuple(islice(it, n))):\n", " yield batch\n", "\n", "\n", "def chunked_tokens(text: str, encoding_name: str = 'cl100k_base', chunk_ctx_length: int = EMBEDDING_CTX_LENGTH):\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " tokens = encoding.encode(text)\n", " chunks_iterator = batched(tokens, chunk_ctx_length)\n", " yield from chunks_iterator\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "import numpy as np\n", "from tenacity import retry, wait_random_exponential, stop_after_attempt\n", "\n", "\n", "@retry(wait=wait_random_exponential(min=1, max=20), stop=stop_after_attempt(6))\n", "def get_embedding(tokens: Sequence[int], model=EMBEDDING_MODEL) -> list[float]:\n", " return openai.Embedding.create(input=tokens, model=model)[\"data\"][0][\"embedding\"]\n", "\n", "\n", "def len_safe_get_embedding(text: str, model=EMBEDDING_MODEL, max_tokens: int = EMBEDDING_CTX_LENGTH, encoding_name: str = 'cl100k_base', reduction: Optional[str]='average'):\n", " chunk_embeddings = []\n", " for chunk in chunked_tokens(text, encoding_name=encoding_name, chunk_ctx_length=max_tokens):\n", " chunk_embeddings.append(get_embedding(chunk, model=model))\n", "\n", " if reduction is None:\n", " return chunk_embeddings\n", " elif reduction == 'average':\n", " return np.mean(chunk_embeddings, weights=[len(c) for c in chunk_embeddings])\n", " else:\n", " raise NotI\n", "\n", "\n", "\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "compare_encodings(\"antidisestablishmentarianism\")\n" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "compare_encodings(\"2 + 2 = 4\")\n" ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "compare_encodings(\"お誕生日おめでとう\")\n" ] }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "long_prompt = str(list(range(3000)))\n", "num_tokens_from_string(long_prompt, 'cl100k_base')" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "import openai\n", "\n", "EMBEDDING_MODEL = 'text-embedding-ada-002'\n", "EMBEDDING_CTX_LENGTH = 8191\n", "\n", "openai.Embedding.create(input=long_prompt, model=EMBEDDING_MODEL)\n", "\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "def truncate_string_tokens(text: str, encoding_name: str = 'cl100k_base', max_tokens: int = EMBEDDING_CTX_LENGTH) -> list[int]:\n", " \"\"\"Truncate a string to have `max_tokens` according to the given encoding.\"\"\"\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " return encoding.encode(text)[:max_tokens]\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "from itertools import islice\n", "\n", "# From: https://docs.python.org/3/library/itertools.html#itertools-recipes\n", "def batched(iterable, n):\n", " \"\"\"Batch data into tuples of length n. The last batch may be shorter.\"\"\"\n", " # batched('ABCDEFG', 3) --> ABC DEF G\n", " if n < 1:\n", " raise ValueError('n must be at least one')\n", " it = iter(iterable)\n", " while (batch := tuple(islice(it, n))):\n", " yield batch\n", "\n", "\n", "def chunked_tokens(text: str, encoding_name: str = 'cl100k_base', chunk_ctx_length: int = EMBEDDING_CTX_LENGTH):\n", " encoding = tiktoken.get_encoding(encoding_name)\n", " tokens = encoding.encode(text)\n", " chunks_iterator = batched(tokens, chunk_ctx_length)\n", " yield from chunks_iterator\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [ "import numpy as np\n", "from tenacity import retry, wait_random_exponential, stop_after_attempt\n", "\n", "\n", "@retry(wait=wait_random_exponential(min=1, max=20), stop=stop_after_attempt(6))\n", "def get_embedding(tokens: Sequence[int], model=EMBEDDING_MODEL) -> list[float]:\n", " return openai.Embedding.create(input=tokens, model=model)[\"data\"][0][\"embedding\"]\n", "\n", "\n", "def len_safe_get_embedding(text: str, model=EMBEDDING_MODEL, max_tokens: int = EMBEDDING_CTX_LENGTH, encoding_name: str = 'cl100k_base', reduction: Optional[str] = None):\n", " chunk_embeddings = []\n", " for chunk in chunked_tokens(text, encoding_name=encoding_name, chunk_ctx_length=max_tokens):\n", " chunk_embeddings.append(get_embedding(chunk, model=model))\n", "\n", " if reduction is None:\n", " return chunk_embeddings\n", " elif reduction == 'average':\n", " return np.average(chunk_embeddings, axis=0, weights=[len(c) for c in chunk_embeddings]).tolist()\n", " else:\n", " raise ValueError(f'reduction {reduction} not valid.')\n", "\n", "\n", "\n" ], "metadata": { "collapsed": false } }, { "cell_type": "code", "execution_count": null, "outputs": [], "source": [], "metadata": { "collapsed": false } } ], "metadata": { "kernelspec": { "display_name": "openai", "language": "python", "name": "python3" }, "language_info": { "codemirror_mode": { "name": "ipython", "version": 3 }, "file_extension": ".py", "mimetype": "text/x-python", "name": "python", "nbconvert_exporter": "python", "pygments_lexer": "ipython3", "version": "3.9.9" }, "orig_nbformat": 4, "vscode": { "interpreter": { "hash": "365536dcbde60510dc9073d6b991cd35db2d9bac356a11f5b64279a5e6708b97" } } }, "nbformat": 4, "nbformat_minor": 2 }