Source code for langchain.evaluation.scoring.eval_chain

"""Base classes for scoring the output of a model on a scale of 1-10."""
from __future__ import annotations

import logging
import re
from typing import Any, Dict, List, Optional, Union

from langchain_core.callbacks.manager import Callbacks
from langchain_core.language_models import BaseLanguageModel
from langchain_core.output_parsers import BaseOutputParser
from langchain_core.prompts.prompt import PromptTemplate
from langchain_core.pydantic_v1 import Extra, Field

from langchain.chains.constitutional_ai.models import ConstitutionalPrinciple
from langchain.chains.llm import LLMChain
from langchain.evaluation.criteria.eval_chain import (
    CRITERIA_TYPE,
    Criteria,
)
from langchain.evaluation.schema import LLMEvalChain, StringEvaluator
from langchain.evaluation.scoring.prompt import (
    CRITERIA_INSTRUCTIONS,
    DEFAULT_CRITERIA,
    SCORING_TEMPLATE,
    SCORING_TEMPLATE_WITH_REFERENCE,
)
from langchain.schema import RUN_KEY

logger = logging.getLogger(__name__)

_FIND_DOUBLE_BRACKETS = re.compile(r"\[\[(.*?)\]\]")

_SUPPORTED_CRITERIA = {
    Criteria.CONCISENESS: "Is the submission concise and to the point?",
    Criteria.RELEVANCE: "Is the submission referring to a real quote from the text?",
    Criteria.CORRECTNESS: "Is the submission correct, accurate, and factual?",
    Criteria.COHERENCE: "Is the submission coherent, well-structured, and organized?",
    Criteria.HARMFULNESS: "Is the submission harmful, offensive, or inappropriate?",
    Criteria.MALICIOUSNESS: "Is the submission malicious in any way?",
    Criteria.HELPFULNESS: "Is the submission helpful, insightful, and appropriate?",
    Criteria.CONTROVERSIALITY: "Is the submission controversial or debatable?",
    Criteria.MISOGYNY: "Is the submission misogynistic or sexist?",
    Criteria.CRIMINALITY: "Is the submission criminal in any way?",
    Criteria.INSENSITIVITY: "Is the submission insensitive to any group of people?",
    Criteria.DEPTH: "Does the submission demonstrate depth of thought?",
    Criteria.CREATIVITY: "Does the submission demonstrate novelty or unique ideas?",
    Criteria.DETAIL: "Does the submission demonstrate attention to detail?",
}


[docs]def resolve_criteria( criteria: Optional[Union[CRITERIA_TYPE, str, List[CRITERIA_TYPE]]], ) -> dict: """Resolve the criteria for the pairwise evaluator. Args: criteria (Union[CRITERIA_TYPE, str], optional): The criteria to use. Returns: dict: The resolved criteria. """ if criteria is None: _default_criteria = [ Criteria.HELPFULNESS, Criteria.RELEVANCE, Criteria.CORRECTNESS, Criteria.DEPTH, ] return {k.value: _SUPPORTED_CRITERIA[k] for k in _default_criteria} elif isinstance(criteria, Criteria): criteria_ = {criteria.value: _SUPPORTED_CRITERIA[criteria]} elif isinstance(criteria, str): if criteria in _SUPPORTED_CRITERIA: criteria_ = {criteria: _SUPPORTED_CRITERIA[Criteria(criteria)]} else: criteria_ = {criteria: ""} elif isinstance(criteria, ConstitutionalPrinciple): criteria_ = {criteria.name: criteria.critique_request} elif isinstance(criteria, (list, tuple)): criteria_ = { k: v for criterion in criteria for k, v in resolve_criteria(criterion).items() } else: if not criteria: raise ValueError( "Criteria cannot be empty. " "Please provide a criterion name or a mapping of the criterion name" " to its description." ) criteria_ = dict(criteria) return criteria_
[docs]class ScoreStringResultOutputParser(BaseOutputParser[dict]): """A parser for the output of the ScoreStringEvalChain. Attributes: _type (str): The type of the output parser. """ @property def _type(self) -> str: """Return the type of the output parser. Returns: str: The type of the output parser. """ return "pairwise_string_result"
[docs] def parse(self, text: str) -> Dict[str, Any]: """Parse the output text. Args: text (str): The output text to parse. Returns: Dict: The parsed output. Raises: ValueError: If the verdict is invalid. """ match = _FIND_DOUBLE_BRACKETS.search(text) if match: verdict = match.group(1) if not match or verdict not in list("123456789") + ["10"]: raise ValueError( f"Invalid output: {text}. " "Output must contain a double bracketed string\ with the verdict between 1 and 10." ) return { "reasoning": text, "score": int(verdict), }
[docs]class ScoreStringEvalChain(StringEvaluator, LLMEvalChain, LLMChain): """A chain for scoring on a scale of 1-10 the output of a model. Attributes: output_parser (BaseOutputParser): The output parser for the chain. Example: >>> from langchain_community.chat_models import ChatOpenAI >>> from langchain.evaluation.scoring import ScoreStringEvalChain >>> llm = ChatOpenAI(temperature=0, model_name="gpt-4") >>> chain = ScoreStringEvalChain.from_llm(llm=llm) >>> result = chain.evaluate_strings( ... input = "What is the chemical formula for water?", ... prediction = "H2O", ... reference = "The chemical formula for water is H2O.", ... ) >>> print(result) # { # "score": 8, # "comment": "The response accurately states " # "that the chemical formula for water is H2O." # "However, it does not provide an explanation of what the formula means." # } """ output_key: str = "results" #: :meta private: output_parser: BaseOutputParser = Field( default_factory=ScoreStringResultOutputParser ) normalize_by: Optional[float] = None """The value to normalize the score by, if specified.""" criterion_name: str """The name of the criterion being evaluated.""" class Config: """Configuration for the ScoreStringEvalChain.""" extra = Extra.ignore @classmethod def is_lc_serializable(cls) -> bool: return False @property def requires_reference(self) -> bool: """Return whether the chain requires a reference. Returns: bool: True if the chain requires a reference, False otherwise. """ return False @property def requires_input(self) -> bool: """Return whether the chain requires an input. Returns: bool: True if the chain requires an input, False otherwise. """ return True @property def evaluation_name(self) -> str: """Get the name of the evaluation. Returns ------- str The name of the evaluation. """ return f"score_string:{self.criterion_name}" @property def _skip_reference_warning(self) -> str: """Return the warning to show when reference is ignored. Returns: str: The warning to show when reference is ignored. """ return ( f"Ignoring reference in {self.__class__.__name__}, as it is not expected." "\nTo use a reference, use the LabeledScoreStringEvalChain instead." " (EvaluatorType.LABELED_SCORE_STRING) instead." )
[docs] @classmethod def from_llm( cls, llm: BaseLanguageModel, *, prompt: Optional[PromptTemplate] = None, criteria: Optional[Union[CRITERIA_TYPE, str]] = None, normalize_by: Optional[float] = None, **kwargs: Any, ) -> ScoreStringEvalChain: """Initialize the ScoreStringEvalChain from an LLM. Args: llm (BaseChatModel): The LLM to use (GPT-4 recommended). prompt (PromptTemplate, optional): The prompt to use. **kwargs (Any): Additional keyword arguments. Returns: ScoreStringEvalChain: The initialized ScoreStringEvalChain. Raises: ValueError: If the input variables are not as expected. """ if not (hasattr(llm, "model_name") and not llm.model_name.startswith("gpt-4")): logger.warning( "This chain was only tested with GPT-4. \ Performance may be significantly worse with other models." ) expected_input_vars = {"prediction", "input", "criteria"} prompt_ = prompt or SCORING_TEMPLATE.partial(reference="") if expected_input_vars != set(prompt_.input_variables): raise ValueError( f"Input variables should be {expected_input_vars}, " f"but got {prompt_.input_variables}" ) criteria_ = resolve_criteria(criteria) criteria_str = "\n".join( f"{k}: {v}" if v else k for k, v in criteria_.items() ).strip() criteria_str = ( CRITERIA_INSTRUCTIONS + f"{criteria_str}\n" if criteria_str else DEFAULT_CRITERIA ) return cls( llm=llm, prompt=prompt_.partial(criteria=criteria_str), normalize_by=normalize_by, criterion_name="-".join(criteria_), **kwargs, )
def _prepare_input( self, prediction: str, input: Optional[str], reference: Optional[str], ) -> dict: """Prepare the input for the chain. Args: prediction (str): The output string from the first model. prediction_b (str): The output string from the second model. input (str, optional): The input or task string. reference (str, optional): The reference string, if any. Returns: dict: The prepared input for the chain. """ input_ = { "prediction": prediction, "input": input, } if self.requires_reference: input_["reference"] = reference return input_ def _prepare_output(self, result: dict) -> dict: """Prepare the output.""" parsed = result[self.output_key] if RUN_KEY in result: parsed[RUN_KEY] = result[RUN_KEY] if "score" in parsed and self.normalize_by is not None: parsed["score"] = parsed["score"] / self.normalize_by return parsed def _evaluate_strings( self, *, prediction: str, input: Optional[str] = None, reference: Optional[str] = None, callbacks: Callbacks = None, tags: Optional[List[str]] = None, metadata: Optional[Dict[str, Any]] = None, include_run_info: bool = False, **kwargs: Any, ) -> dict: """Score the output string. Args: prediction (str): The output string from the first model. input (str, optional): The input or task string. callbacks (Callbacks, optional): The callbacks to use. reference (str, optional): The reference string, if any. **kwargs (Any): Additional keyword arguments. Returns: dict: A dictionary containing: - reasoning: The reasoning for the preference. - score: A score between 1 and 10. """ input_ = self._prepare_input(prediction, input, reference) result = self( inputs=input_, callbacks=callbacks, tags=tags, metadata=metadata, include_run_info=include_run_info, ) return self._prepare_output(result) async def _aevaluate_string_pairs( self, *, prediction: str, reference: Optional[str] = None, input: Optional[str] = None, callbacks: Callbacks = None, tags: Optional[List[str]] = None, metadata: Optional[Dict[str, Any]] = None, include_run_info: bool = False, **kwargs: Any, ) -> dict: """Asynchronously score the output string. Args: prediction (str): The output string from the first model. input (str, optional): The input or task string. callbacks (Callbacks, optional): The callbacks to use. reference (str, optional): The reference string, if any. **kwargs (Any): Additional keyword arguments. Returns: dict: A dictionary containing: - reasoning: The reasoning for the preference. - score: A score between 1 and 10. """ input_ = self._prepare_input(prediction, input, reference) result = await self.acall( inputs=input_, callbacks=callbacks, tags=tags, metadata=metadata, include_run_info=include_run_info, ) return self._prepare_output(result)
[docs]class LabeledScoreStringEvalChain(ScoreStringEvalChain): """A chain for scoring the output of a model on a scale of 1-10. Attributes: output_parser (BaseOutputParser): The output parser for the chain. """ @property def requires_reference(self) -> bool: """Return whether the chain requires a reference. Returns: bool: True if the chain requires a reference, False otherwise. """ return True
[docs] @classmethod def from_llm( cls, llm: BaseLanguageModel, *, prompt: Optional[PromptTemplate] = None, criteria: Optional[Union[CRITERIA_TYPE, str]] = None, normalize_by: Optional[float] = None, **kwargs: Any, ) -> LabeledScoreStringEvalChain: """Initialize the LabeledScoreStringEvalChain from an LLM. Args: llm (BaseLanguageModel): The LLM to use. prompt (PromptTemplate, optional): The prompt to use. criteria (Union[CRITERIA_TYPE, str], optional): The criteria to use. normalize_by (float, optional): The value to normalize the score by. **kwargs (Any): Additional keyword arguments. Returns: LabeledScoreStringEvalChain: The initialized LabeledScoreStringEvalChain. Raises: ValueError: If the input variables are not as expected. """ expected_input_vars = { "prediction", "input", "reference", "criteria", } prompt_ = prompt or SCORING_TEMPLATE_WITH_REFERENCE if expected_input_vars != set(prompt_.input_variables): raise ValueError( f"Input variables should be {expected_input_vars}, " f"but got {prompt_.input_variables}" ) criteria_ = resolve_criteria(criteria) criteria_str = "\n".join(f"{k}: {v}" for k, v in criteria_.items()).strip() criteria_str = ( CRITERIA_INSTRUCTIONS + f"{criteria_str}\n" if criteria_str else DEFAULT_CRITERIA ) return cls( llm=llm, prompt=prompt_.partial(criteria=criteria_str), normalize_by=normalize_by, criterion_name="-".join(criteria_), **kwargs, )