"""Question answering with sources over documents."""
from __future__ import annotations
import inspect
import re
from abc import ABC, abstractmethod
from typing import Any, Dict, List, Optional, Tuple
from langchain_core._api import deprecated
from langchain_core.callbacks import (
AsyncCallbackManagerForChainRun,
CallbackManagerForChainRun,
)
from langchain_core.documents import Document
from langchain_core.language_models import BaseLanguageModel
from langchain_core.prompts import BasePromptTemplate
from pydantic import ConfigDict, model_validator
from langchain.chains import ReduceDocumentsChain
from langchain.chains.base import Chain
from langchain.chains.combine_documents.base import BaseCombineDocumentsChain
from langchain.chains.combine_documents.map_reduce import MapReduceDocumentsChain
from langchain.chains.combine_documents.stuff import StuffDocumentsChain
from langchain.chains.llm import LLMChain
from langchain.chains.qa_with_sources.loading import load_qa_with_sources_chain
from langchain.chains.qa_with_sources.map_reduce_prompt import (
COMBINE_PROMPT,
EXAMPLE_PROMPT,
QUESTION_PROMPT,
)
[docs]
@deprecated(
since="0.2.13",
removal="1.0",
message=(
"This class is deprecated. Refer to this guide on retrieval and question "
"answering with sources: "
"https://python.langchain.com/docs/how_to/qa_sources/"
),
)
class BaseQAWithSourcesChain(Chain, ABC):
"""Question answering chain with sources over documents."""
combine_documents_chain: BaseCombineDocumentsChain
"""Chain to use to combine documents."""
question_key: str = "question" #: :meta private:
input_docs_key: str = "docs" #: :meta private:
answer_key: str = "answer" #: :meta private:
sources_answer_key: str = "sources" #: :meta private:
return_source_documents: bool = False
"""Return the source documents."""
[docs]
@classmethod
def from_llm(
cls,
llm: BaseLanguageModel,
document_prompt: BasePromptTemplate = EXAMPLE_PROMPT,
question_prompt: BasePromptTemplate = QUESTION_PROMPT,
combine_prompt: BasePromptTemplate = COMBINE_PROMPT,
**kwargs: Any,
) -> BaseQAWithSourcesChain:
"""Construct the chain from an LLM."""
llm_question_chain = LLMChain(llm=llm, prompt=question_prompt)
llm_combine_chain = LLMChain(llm=llm, prompt=combine_prompt)
combine_results_chain = StuffDocumentsChain(
llm_chain=llm_combine_chain,
document_prompt=document_prompt,
document_variable_name="summaries",
)
reduce_documents_chain = ReduceDocumentsChain( # type: ignore[misc]
combine_documents_chain=combine_results_chain
)
combine_documents_chain = MapReduceDocumentsChain(
llm_chain=llm_question_chain,
reduce_documents_chain=reduce_documents_chain,
document_variable_name="context",
)
return cls(
combine_documents_chain=combine_documents_chain,
**kwargs,
)
[docs]
@classmethod
def from_chain_type(
cls,
llm: BaseLanguageModel,
chain_type: str = "stuff",
chain_type_kwargs: Optional[dict] = None,
**kwargs: Any,
) -> BaseQAWithSourcesChain:
"""Load chain from chain type."""
_chain_kwargs = chain_type_kwargs or {}
combine_documents_chain = load_qa_with_sources_chain(
llm, chain_type=chain_type, **_chain_kwargs
)
return cls(combine_documents_chain=combine_documents_chain, **kwargs)
model_config = ConfigDict(
arbitrary_types_allowed=True,
extra="forbid",
)
@property
def input_keys(self) -> List[str]:
"""Expect input key.
:meta private:
"""
return [self.question_key]
@property
def output_keys(self) -> List[str]:
"""Return output key.
:meta private:
"""
_output_keys = [self.answer_key, self.sources_answer_key]
if self.return_source_documents:
_output_keys = _output_keys + ["source_documents"]
return _output_keys
@model_validator(mode="before")
@classmethod
def validate_naming(cls, values: Dict) -> Any:
"""Fix backwards compatibility in naming."""
if "combine_document_chain" in values:
values["combine_documents_chain"] = values.pop("combine_document_chain")
return values
def _split_sources(self, answer: str) -> Tuple[str, str]:
"""Split sources from answer."""
if re.search(r"SOURCES?:", answer, re.IGNORECASE):
answer, sources = re.split(
r"SOURCES?:|QUESTION:\s", answer, flags=re.IGNORECASE
)[:2]
sources = re.split(r"\n", sources)[0].strip()
else:
sources = ""
return answer, sources
@abstractmethod
def _get_docs(
self,
inputs: Dict[str, Any],
*,
run_manager: CallbackManagerForChainRun,
) -> List[Document]:
"""Get docs to run questioning over."""
def _call(
self,
inputs: Dict[str, Any],
run_manager: Optional[CallbackManagerForChainRun] = None,
) -> Dict[str, str]:
_run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
accepts_run_manager = (
"run_manager" in inspect.signature(self._get_docs).parameters
)
if accepts_run_manager:
docs = self._get_docs(inputs, run_manager=_run_manager)
else:
docs = self._get_docs(inputs) # type: ignore[call-arg]
answer = self.combine_documents_chain.run(
input_documents=docs, callbacks=_run_manager.get_child(), **inputs
)
answer, sources = self._split_sources(answer)
result: Dict[str, Any] = {
self.answer_key: answer,
self.sources_answer_key: sources,
}
if self.return_source_documents:
result["source_documents"] = docs
return result
@abstractmethod
async def _aget_docs(
self,
inputs: Dict[str, Any],
*,
run_manager: AsyncCallbackManagerForChainRun,
) -> List[Document]:
"""Get docs to run questioning over."""
async def _acall(
self,
inputs: Dict[str, Any],
run_manager: Optional[AsyncCallbackManagerForChainRun] = None,
) -> Dict[str, Any]:
_run_manager = run_manager or AsyncCallbackManagerForChainRun.get_noop_manager()
accepts_run_manager = (
"run_manager" in inspect.signature(self._aget_docs).parameters
)
if accepts_run_manager:
docs = await self._aget_docs(inputs, run_manager=_run_manager)
else:
docs = await self._aget_docs(inputs) # type: ignore[call-arg]
answer = await self.combine_documents_chain.arun(
input_documents=docs, callbacks=_run_manager.get_child(), **inputs
)
answer, sources = self._split_sources(answer)
result: Dict[str, Any] = {
self.answer_key: answer,
self.sources_answer_key: sources,
}
if self.return_source_documents:
result["source_documents"] = docs
return result
[docs]
@deprecated(
since="0.2.13",
removal="1.0",
message=(
"This class is deprecated. Refer to this guide on retrieval and question "
"answering with sources: "
"https://python.langchain.com/docs/how_to/qa_sources/"
),
)
class QAWithSourcesChain(BaseQAWithSourcesChain):
"""Question answering with sources over documents."""
input_docs_key: str = "docs" #: :meta private:
@property
def input_keys(self) -> List[str]:
"""Expect input key.
:meta private:
"""
return [self.input_docs_key, self.question_key]
def _get_docs(
self,
inputs: Dict[str, Any],
*,
run_manager: CallbackManagerForChainRun,
) -> List[Document]:
"""Get docs to run questioning over."""
return inputs.pop(self.input_docs_key)
async def _aget_docs(
self,
inputs: Dict[str, Any],
*,
run_manager: AsyncCallbackManagerForChainRun,
) -> List[Document]:
"""Get docs to run questioning over."""
return inputs.pop(self.input_docs_key)
@property
def _chain_type(self) -> str:
return "qa_with_sources_chain"
