81 lines
2.8 KiB
Python
81 lines
2.8 KiB
Python
from typing import Dict, List
|
|
from guardrails.logger import logger
|
|
|
|
import tiktoken
|
|
|
|
|
|
def num_tokens_from_string(text: str, model_name: str) -> int:
|
|
"""Returns the number of tokens in a text string.
|
|
|
|
Supported for OpenAI models only. This is a helper function
|
|
that is required when OpenAI's `stream` parameter is set to `True`,
|
|
because OpenAI does not return the number of tokens in that case.
|
|
Requires the `tiktoken` package to be installed.
|
|
|
|
Args:
|
|
text (str): The text string to count the number of tokens in.
|
|
model_name (str): The name of the OpenAI model to use.
|
|
|
|
Returns:
|
|
num_tokens (int): The number of tokens in the text string.
|
|
"""
|
|
encoding = tiktoken.encoding_for_model(model_name)
|
|
num_tokens = len(encoding.encode(text))
|
|
return num_tokens
|
|
|
|
|
|
def num_tokens_from_messages(
|
|
messages: List[Dict[str, str]], model: str = "gpt-3.5-turbo-0613"
|
|
) -> int:
|
|
"""Return the number of tokens used by a list of messages."""
|
|
try:
|
|
encoding = tiktoken.encoding_for_model(model)
|
|
except KeyError:
|
|
logger.warning("model not found. Using cl100k_base encoding.")
|
|
encoding = tiktoken.get_encoding("cl100k_base")
|
|
if model in {
|
|
"gpt-3.5-turbo-0613",
|
|
"gpt-3.5-turbo-16k-0613",
|
|
"gpt-4-0314",
|
|
"gpt-4-32k-0314",
|
|
"gpt-4-0613",
|
|
"gpt-4-32k-0613",
|
|
}:
|
|
tokens_per_message = 3
|
|
tokens_per_name = 1
|
|
elif model == "gpt-3.5-turbo-0301":
|
|
tokens_per_message = (
|
|
4 # every message follows <|start|>{role/name}\n{content}<|end|>\n
|
|
)
|
|
tokens_per_name = -1 # if there's a name, the role is omitted
|
|
elif "gpt-3.5-turbo" in model:
|
|
logger.warning(
|
|
"""gpt-3.5-turbo may update over time.
|
|
Returning num tokens assuming gpt-3.5-turbo-0613."""
|
|
)
|
|
return num_tokens_from_messages(messages, model="gpt-3.5-turbo-0613")
|
|
elif "gpt-4" in model:
|
|
logger.warning(
|
|
"""gpt-4 may update over time.
|
|
Returning num tokens assuming gpt-4-0613."""
|
|
)
|
|
return num_tokens_from_messages(messages, model="gpt-4-0613")
|
|
else:
|
|
raise NotImplementedError(
|
|
f"""num_tokens_from_messages() is not implemented for model {model}.
|
|
See https://github.com/openai/openai-python/blob/main/chatml.md for
|
|
information on how messages are converted to tokens."""
|
|
)
|
|
|
|
num_tokens = 0
|
|
for message in messages:
|
|
num_tokens += tokens_per_message
|
|
for key, value in message.items():
|
|
num_tokens += len(encoding.encode(value))
|
|
if key == "name":
|
|
num_tokens += tokens_per_name
|
|
|
|
# every reply is primed with <|start|>assistant<|message|>
|
|
num_tokens += 3
|
|
return num_tokens
|