Langchain PDF Chatbot 만들기 - 23 - Custom LLM 만들기
목차
Custom Chat Model 만들게 된 이유
기존에는 text-generation task 모델을 사용했는데 사용하고 싶은 모델의 task가 image-text-to-text로 되어 있어서 HuggingFacePipeline에서 지원을 안함
HuggingFacePipeline는 text-generation, text2text-generation, summarization, translation task만 지원을 하고 있음
Google, Meta 등이 만드는 모델은 멀티모달로 나오는데 이 부분이 해결이 되면 좋겠음
Custom Chat Model
처음에는 custom LLM class를 만들어야하는 줄 알았음
하지만 채팅 완성을 하는데 더 특화되어서 custom chat model이 있었음
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from typing import Any, Dict, Iterator, List, Optional
from langchain_core.callbacks import (
CallbackManagerForLLMRun,
)
from langchain_core.language_models import BaseChatModel
from langchain_core.messages import (
AIMessage,
AIMessageChunk,
BaseMessage,
)
from langchain_core.messages.ai import UsageMetadata
from langchain_core.outputs import ChatGeneration, ChatGenerationChunk, ChatResult
from pydantic import Field
class ChatParrotLink(BaseChatModel):
"""A custom chat model that echoes the first `parrot_buffer_length` characters
of the input.
When contributing an implementation to LangChain, carefully document
the model including the initialization parameters, include
an example of how to initialize the model and include any relevant
links to the underlying models documentation or API.
Example:
.. code-block:: python
model = ChatParrotLink(parrot_buffer_length=2, model="bird-brain-001")
result = model.invoke([HumanMessage(content="hello")])
result = model.batch([[HumanMessage(content="hello")],
[HumanMessage(content="world")]])
"""
model_name: str = Field(alias="model")
"""The name of the model"""
parrot_buffer_length: int
"""The number of characters from the last message of the prompt to be echoed."""
temperature: Optional[float] = None
max_tokens: Optional[int] = None
timeout: Optional[int] = None
stop: Optional[List[str]] = None
max_retries: int = 2
def _generate(
self,
messages: List[BaseMessage],
stop: Optional[List[str]] = None,
run_manager: Optional[CallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> ChatResult:
"""Override the _generate method to implement the chat model logic.
This can be a call to an API, a call to a local model, or any other
implementation that generates a response to the input prompt.
Args:
messages: the prompt composed of a list of messages.
stop: a list of strings on which the model should stop generating.
If generation stops due to a stop token, the stop token itself
SHOULD BE INCLUDED as part of the output. This is not enforced
across models right now, but it's a good practice to follow since
it makes it much easier to parse the output of the model
downstream and understand why generation stopped.
run_manager: A run manager with callbacks for the LLM.
"""
# Replace this with actual logic to generate a response from a list
# of messages.
last_message = messages[-1]
tokens = last_message.content[: self.parrot_buffer_length]
ct_input_tokens = sum(len(message.content) for message in messages)
ct_output_tokens = len(tokens)
message = AIMessage(
content=tokens,
additional_kwargs={}, # Used to add additional payload to the message
response_metadata={ # Use for response metadata
"time_in_seconds": 3,
"model_name": self.model_name,
},
usage_metadata={
"input_tokens": ct_input_tokens,
"output_tokens": ct_output_tokens,
"total_tokens": ct_input_tokens + ct_output_tokens,
},
)
##
generation = ChatGeneration(message=message)
return ChatResult(generations=[generation])
def _stream(
self,
messages: List[BaseMessage],
stop: Optional[List[str]] = None,
run_manager: Optional[CallbackManagerForLLMRun] = None,
**kwargs: Any,
) -> Iterator[ChatGenerationChunk]:
"""Stream the output of the model.
This method should be implemented if the model can generate output
in a streaming fashion. If the model does not support streaming,
do not implement it. In that case streaming requests will be automatically
handled by the _generate method.
Args:
messages: the prompt composed of a list of messages.
stop: a list of strings on which the model should stop generating.
If generation stops due to a stop token, the stop token itself
SHOULD BE INCLUDED as part of the output. This is not enforced
across models right now, but it's a good practice to follow since
it makes it much easier to parse the output of the model
downstream and understand why generation stopped.
run_manager: A run manager with callbacks for the LLM.
"""
last_message = messages[-1]
tokens = str(last_message.content[: self.parrot_buffer_length])
ct_input_tokens = sum(len(message.content) for message in messages)
for token in tokens:
usage_metadata = UsageMetadata(
{
"input_tokens": ct_input_tokens,
"output_tokens": 1,
"total_tokens": ct_input_tokens + 1,
}
)
ct_input_tokens = 0
chunk = ChatGenerationChunk(
message=AIMessageChunk(content=token, usage_metadata=usage_metadata)
)
if run_manager:
# This is optional in newer versions of LangChain
# The on_llm_new_token will be called automatically
run_manager.on_llm_new_token(token, chunk=chunk)
yield chunk
# Let's add some other information (e.g., response metadata)
chunk = ChatGenerationChunk(
message=AIMessageChunk(
content="",
response_metadata={"time_in_sec": 3, "model_name": self.model_name},
)
)
if run_manager:
# This is optional in newer versions of LangChain
# The on_llm_new_token will be called automatically
run_manager.on_llm_new_token(token, chunk=chunk)
yield chunk
@property
def _llm_type(self) -> str:
"""Get the type of language model used by this chat model."""
return "echoing-chat-model-advanced"
@property
def _identifying_params(self) -> Dict[str, Any]:
"""Return a dictionary of identifying parameters.
This information is used by the LangChain callback system, which
is used for tracing purposes make it possible to monitor LLMs.
"""
return {
# The model name allows users to specify custom token counting
# rules in LLM monitoring applications (e.g., in LangSmith users
# can provide per token pricing for their model and monitor
# costs for the given LLM.)
"model_name": self.model_name,
}
해당 코드를 수정해서 사용했음
_generate, _llm_type은 class 내부에 필수로 있어야하고
_identifying_params, _stream, _agenerate, _astream 은 필수는 아님