Source code for langchain_experimental.rl_chain.base

from __future__ import annotations

import logging
import os
from abc import ABC, abstractmethod
from typing import (
    TYPE_CHECKING,
    Any,
    Dict,
    Generic,
    List,
    Optional,
    Tuple,
    Type,
    TypeVar,
    Union,
)

from langchain.chains.base import Chain
from langchain.chains.llm import LLMChain
from langchain_core.callbacks.manager import CallbackManagerForChainRun
from langchain_core.prompts import (
    BasePromptTemplate,
    ChatPromptTemplate,
    HumanMessagePromptTemplate,
    SystemMessagePromptTemplate,
)

from langchain_experimental.pydantic_v1 import BaseModel, Extra, root_validator
from langchain_experimental.rl_chain.metrics import (
    MetricsTrackerAverage,
    MetricsTrackerRollingWindow,
)
from langchain_experimental.rl_chain.model_repository import ModelRepository
from langchain_experimental.rl_chain.vw_logger import VwLogger

if TYPE_CHECKING:
    import vowpal_wabbit_next as vw

logger = logging.getLogger(__name__)


class _BasedOn:
    def __init__(self, value: Any):
        self.value = value

    def __str__(self) -> str:
        return str(self.value)

    __repr__ = __str__


[docs]def BasedOn(anything: Any) -> _BasedOn: """Wrap a value to indicate that it should be based on.""" return _BasedOn(anything)
class _ToSelectFrom: def __init__(self, value: Any): self.value = value def __str__(self) -> str: return str(self.value) __repr__ = __str__
[docs]def ToSelectFrom(anything: Any) -> _ToSelectFrom: """Wrap a value to indicate that it should be selected from.""" if not isinstance(anything, list): raise ValueError("ToSelectFrom must be a list to select from") return _ToSelectFrom(anything)
class _Embed: def __init__(self, value: Any, keep: bool = False): self.value = value self.keep = keep def __str__(self) -> str: return str(self.value) __repr__ = __str__
[docs]def Embed(anything: Any, keep: bool = False) -> Any: """Wrap a value to indicate that it should be embedded.""" if isinstance(anything, _ToSelectFrom): return ToSelectFrom(Embed(anything.value, keep=keep)) elif isinstance(anything, _BasedOn): return BasedOn(Embed(anything.value, keep=keep)) if isinstance(anything, list): return [Embed(v, keep=keep) for v in anything] elif isinstance(anything, dict): return {k: Embed(v, keep=keep) for k, v in anything.items()} elif isinstance(anything, _Embed): return anything return _Embed(anything, keep=keep)
[docs]def EmbedAndKeep(anything: Any) -> Any: """Wrap a value to indicate that it should be embedded and kept.""" return Embed(anything, keep=True)
# helper functions
[docs]def stringify_embedding(embedding: List) -> str: """Convert an embedding to a string.""" return " ".join([f"{i}:{e}" for i, e in enumerate(embedding)])
[docs]def parse_lines(parser: "vw.TextFormatParser", input_str: str) -> List["vw.Example"]: """Parse the input string into a list of examples.""" return [parser.parse_line(line) for line in input_str.split("\n")]
[docs]def get_based_on_and_to_select_from(inputs: Dict[str, Any]) -> Tuple[Dict, Dict]: """Get the BasedOn and ToSelectFrom from the inputs.""" to_select_from = { k: inputs[k].value for k in inputs.keys() if isinstance(inputs[k], _ToSelectFrom) } if not to_select_from: raise ValueError( "No variables using 'ToSelectFrom' found in the inputs. Please include at least one variable containing a list to select from." # noqa: E501 ) based_on = { k: inputs[k].value if isinstance(inputs[k].value, list) else [inputs[k].value] for k in inputs.keys() if isinstance(inputs[k], _BasedOn) } return based_on, to_select_from
[docs]def prepare_inputs_for_autoembed(inputs: Dict[str, Any]) -> Dict[str, Any]: """Prepare the inputs for auto embedding. Go over all the inputs and if something is either wrapped in _ToSelectFrom or _BasedOn, and if their inner values are not already _Embed, then wrap them in EmbedAndKeep while retaining their _ToSelectFrom or _BasedOn status """ # noqa: E501 next_inputs = inputs.copy() for k, v in next_inputs.items(): if isinstance(v, _ToSelectFrom) or isinstance(v, _BasedOn): if not isinstance(v.value, _Embed): next_inputs[k].value = EmbedAndKeep(v.value) return next_inputs
# end helper functions
[docs]class Selected(ABC): """Abstract class to represent the selected item.""" pass
TSelected = TypeVar("TSelected", bound=Selected)
[docs]class Event(Generic[TSelected], ABC): """Abstract class to represent an event.""" inputs: Dict[str, Any] selected: Optional[TSelected]
[docs] def __init__(self, inputs: Dict[str, Any], selected: Optional[TSelected] = None): self.inputs = inputs self.selected = selected
TEvent = TypeVar("TEvent", bound=Event)
[docs]class Policy(Generic[TEvent], ABC): """Abstract class to represent a policy."""
[docs] def __init__(self, **kwargs: Any): pass
[docs] @abstractmethod def predict(self, event: TEvent) -> Any: ...
[docs] @abstractmethod def learn(self, event: TEvent) -> None: ...
[docs] @abstractmethod def log(self, event: TEvent) -> None: ...
[docs] def save(self) -> None: pass
[docs]class VwPolicy(Policy): """Vowpal Wabbit policy."""
[docs] def __init__( self, model_repo: ModelRepository, vw_cmd: List[str], feature_embedder: Embedder, vw_logger: VwLogger, *args: Any, **kwargs: Any, ): super().__init__(*args, **kwargs) self.model_repo = model_repo self.workspace = self.model_repo.load(vw_cmd) self.feature_embedder = feature_embedder self.vw_logger = vw_logger
[docs] def predict(self, event: TEvent) -> Any: import vowpal_wabbit_next as vw text_parser = vw.TextFormatParser(self.workspace) return self.workspace.predict_one( parse_lines(text_parser, self.feature_embedder.format(event)) )
[docs] def learn(self, event: TEvent) -> None: import vowpal_wabbit_next as vw vw_ex = self.feature_embedder.format(event) text_parser = vw.TextFormatParser(self.workspace) multi_ex = parse_lines(text_parser, vw_ex) self.workspace.learn_one(multi_ex)
[docs] def log(self, event: TEvent) -> None: if self.vw_logger.logging_enabled(): vw_ex = self.feature_embedder.format(event) self.vw_logger.log(vw_ex)
[docs] def save(self) -> None: self.model_repo.save(self.workspace)
[docs]class Embedder(Generic[TEvent], ABC): """Abstract class to represent an embedder."""
[docs] def __init__(self, *args: Any, **kwargs: Any): pass
[docs] @abstractmethod def format(self, event: TEvent) -> str: ...
[docs]class SelectionScorer(Generic[TEvent], ABC, BaseModel): """Abstract class to grade the chosen selection or the response of the llm."""
[docs] @abstractmethod def score_response( self, inputs: Dict[str, Any], llm_response: str, event: TEvent ) -> float: ...
[docs]class AutoSelectionScorer(SelectionScorer[Event], BaseModel): """Auto selection scorer.""" llm_chain: LLMChain prompt: Union[BasePromptTemplate, None] = None scoring_criteria_template_str: Optional[str] = None
[docs] @staticmethod def get_default_system_prompt() -> SystemMessagePromptTemplate: return SystemMessagePromptTemplate.from_template( "PLEASE RESPOND ONLY WITH A SINGLE FLOAT AND NO OTHER TEXT EXPLANATION\n \ You are a strict judge that is called on to rank a response based on \ given criteria. You must respond with your ranking by providing a \ single float within the range [0, 1], 0 being very bad \ response and 1 being very good response." )
[docs] @staticmethod def get_default_prompt() -> ChatPromptTemplate: human_template = 'Given this based_on "{rl_chain_selected_based_on}" \ as the most important attribute, rank how good or bad this text is: \ "{rl_chain_selected}".' human_message_prompt = HumanMessagePromptTemplate.from_template(human_template) default_system_prompt = AutoSelectionScorer.get_default_system_prompt() chat_prompt = ChatPromptTemplate.from_messages( [default_system_prompt, human_message_prompt] ) return chat_prompt
@root_validator(pre=True) def set_prompt_and_llm_chain(cls, values: Dict[str, Any]) -> Dict[str, Any]: llm = values.get("llm") prompt = values.get("prompt") scoring_criteria_template_str = values.get("scoring_criteria_template_str") if prompt is None and scoring_criteria_template_str is None: prompt = AutoSelectionScorer.get_default_prompt() elif prompt is None and scoring_criteria_template_str is not None: human_message_prompt = HumanMessagePromptTemplate.from_template( scoring_criteria_template_str ) default_system_prompt = AutoSelectionScorer.get_default_system_prompt() prompt = ChatPromptTemplate.from_messages( [default_system_prompt, human_message_prompt] ) values["prompt"] = prompt values["llm_chain"] = LLMChain(llm=llm, prompt=prompt) return values
[docs] def score_response( self, inputs: Dict[str, Any], llm_response: str, event: Event ) -> float: ranking = self.llm_chain.predict(llm_response=llm_response, **inputs) ranking = ranking.strip() try: resp = float(ranking) return resp except Exception as e: raise RuntimeError( f"The auto selection scorer did not manage to score the response, there is always the option to try again or tweak the reward prompt. Error: {e}" # noqa: E501 )
[docs]class RLChain(Chain, Generic[TEvent]): """Chain that leverages the Vowpal Wabbit (VW) model as a learned policy for reinforcement learning. Attributes: - llm_chain (Chain): Represents the underlying Language Model chain. - prompt (BasePromptTemplate): The template for the base prompt. - selection_scorer (Union[SelectionScorer, None]): Scorer for the selection. Can be set to None. - policy (Optional[Policy]): The policy used by the chain to learn to populate a dynamic prompt. - auto_embed (bool): Determines if embedding should be automatic. Default is False. - metrics (Optional[Union[MetricsTrackerRollingWindow, MetricsTrackerAverage]]): Tracker for metrics, can be set to None. Initialization Attributes: - feature_embedder (Embedder): Embedder used for the `BasedOn` and `ToSelectFrom` inputs. - model_save_dir (str, optional): Directory for saving the VW model. Default is the current directory. - reset_model (bool): If set to True, the model starts training from scratch. Default is False. - vw_cmd (List[str], optional): Command line arguments for the VW model. - policy (Type[VwPolicy]): Policy used by the chain. - vw_logs (Optional[Union[str, os.PathLike]]): Path for the VW logs. - metrics_step (int): Step for the metrics tracker. Default is -1. If set without metrics_window_size, average metrics will be tracked, otherwise rolling window metrics will be tracked. - metrics_window_size (int): Window size for the metrics tracker. Default is -1. If set, rolling window metrics will be tracked. Notes: The class initializes the VW model using the provided arguments. If `selection_scorer` is not provided, a warning is logged, indicating that no reinforcement learning will occur unless the `update_with_delayed_score` method is called. """ # noqa: E501 class _NoOpPolicy(Policy): """Placeholder policy that does nothing""" def predict(self, event: TEvent) -> Any: return None def learn(self, event: TEvent) -> None: pass def log(self, event: TEvent) -> None: pass llm_chain: Chain output_key: str = "result" #: :meta private: prompt: BasePromptTemplate selection_scorer: Union[SelectionScorer, None] active_policy: Policy = _NoOpPolicy() auto_embed: bool = False selection_scorer_activated: bool = True selected_input_key = "rl_chain_selected" selected_based_on_input_key = "rl_chain_selected_based_on" metrics: Optional[Union[MetricsTrackerRollingWindow, MetricsTrackerAverage]] = None def __init__( self, feature_embedder: Embedder, model_save_dir: str = "./", reset_model: bool = False, vw_cmd: Optional[List[str]] = None, policy: Type[Policy] = VwPolicy, vw_logs: Optional[Union[str, os.PathLike]] = None, metrics_step: int = -1, metrics_window_size: int = -1, *args: Any, **kwargs: Any, ): super().__init__(*args, **kwargs) if self.selection_scorer is None: logger.warning( "No selection scorer provided, which means that no \ reinforcement learning will be done in the RL chain \ unless update_with_delayed_score is called." ) if isinstance(self.active_policy, RLChain._NoOpPolicy): self.active_policy = policy( model_repo=ModelRepository( model_save_dir, with_history=True, reset=reset_model ), vw_cmd=vw_cmd or [], feature_embedder=feature_embedder, vw_logger=VwLogger(vw_logs), ) if metrics_window_size > 0: self.metrics = MetricsTrackerRollingWindow( step=metrics_step, window_size=metrics_window_size ) else: self.metrics = MetricsTrackerAverage(step=metrics_step) class Config: """Configuration for this pydantic object.""" extra = Extra.forbid arbitrary_types_allowed = True @property def input_keys(self) -> List[str]: """Expect input key. :meta private: """ return [] @property def output_keys(self) -> List[str]: """Expect output key. :meta private: """ return [self.output_key]
[docs] def update_with_delayed_score( self, score: float, chain_response: Dict[str, Any], force_score: bool = False ) -> None: """ Updates the learned policy with the score provided. Will raise an error if selection_scorer is set, and force_score=True was not provided during the method call """ # noqa: E501 if self._can_use_selection_scorer() and not force_score: raise RuntimeError( "The selection scorer is set, and force_score was not set to True. Please set force_score=True to use this function." # noqa: E501 ) if self.metrics: self.metrics.on_feedback(score) event: TEvent = chain_response["selection_metadata"] self._call_after_scoring_before_learning(event=event, score=score) self.active_policy.learn(event=event) self.active_policy.log(event=event)
[docs] def deactivate_selection_scorer(self) -> None: """ Deactivates the selection scorer, meaning that the chain will no longer attempt to use the selection scorer to score responses. """ # noqa: E501 self.selection_scorer_activated = False
[docs] def activate_selection_scorer(self) -> None: """ Activates the selection scorer, meaning that the chain will attempt to use the selection scorer to score responses. """ # noqa: E501 self.selection_scorer_activated = True
[docs] def save_progress(self) -> None: """ This function should be called to save the state of the learned policy model. """ # noqa: E501 self.active_policy.save()
def _validate_inputs(self, inputs: Dict[str, Any]) -> None: super()._validate_inputs(inputs) if ( self.selected_input_key in inputs.keys() or self.selected_based_on_input_key in inputs.keys() ): raise ValueError( f"The rl chain does not accept '{self.selected_input_key}' or '{self.selected_based_on_input_key}' as input keys, they are reserved for internal use during auto reward." # noqa: E501 ) def _can_use_selection_scorer(self) -> bool: """ Returns whether the chain can use the selection scorer to score responses or not. """ # noqa: E501 return self.selection_scorer is not None and self.selection_scorer_activated @abstractmethod def _call_before_predict(self, inputs: Dict[str, Any]) -> TEvent: ... @abstractmethod def _call_after_predict_before_llm( self, inputs: Dict[str, Any], event: TEvent, prediction: Any ) -> Tuple[Dict[str, Any], TEvent]: ... @abstractmethod def _call_after_llm_before_scoring( self, llm_response: str, event: TEvent ) -> Tuple[Dict[str, Any], TEvent]: ... @abstractmethod def _call_after_scoring_before_learning( self, event: TEvent, score: Optional[float] ) -> TEvent: ... def _call( self, inputs: Dict[str, Any], run_manager: Optional[CallbackManagerForChainRun] = None, ) -> Dict[str, Any]: _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager() event: TEvent = self._call_before_predict(inputs=inputs) prediction = self.active_policy.predict(event=event) if self.metrics: self.metrics.on_decision() next_chain_inputs, event = self._call_after_predict_before_llm( inputs=inputs, event=event, prediction=prediction ) t = self.llm_chain.run(**next_chain_inputs, callbacks=_run_manager.get_child()) _run_manager.on_text(t, color="green", verbose=self.verbose) t = t.strip() if self.verbose: _run_manager.on_text("\nCode: ", verbose=self.verbose) output = t _run_manager.on_text("\nAnswer: ", verbose=self.verbose) _run_manager.on_text(output, color="yellow", verbose=self.verbose) next_chain_inputs, event = self._call_after_llm_before_scoring( llm_response=output, event=event ) score = None try: if self._can_use_selection_scorer(): score = self.selection_scorer.score_response( # type: ignore inputs=next_chain_inputs, llm_response=output, event=event ) except Exception as e: logger.info( f"The selection scorer was not able to score, \ and the chain was not able to adjust to this response, error: {e}" ) if self.metrics and score is not None: self.metrics.on_feedback(score) event = self._call_after_scoring_before_learning(score=score, event=event) self.active_policy.learn(event=event) self.active_policy.log(event=event) return {self.output_key: {"response": output, "selection_metadata": event}} @property def _chain_type(self) -> str: return "llm_personalizer_chain"
[docs]def is_stringtype_instance(item: Any) -> bool: """Check if an item is a string.""" return isinstance(item, str) or ( isinstance(item, _Embed) and isinstance(item.value, str) )
[docs]def embed_string_type( item: Union[str, _Embed], model: Any, namespace: Optional[str] = None ) -> Dict[str, Union[str, List[str]]]: """Embed a string or an _Embed object.""" keep_str = "" if isinstance(item, _Embed): encoded = stringify_embedding(model.encode(item.value)) if item.keep: keep_str = item.value.replace(" ", "_") + " " elif isinstance(item, str): encoded = item.replace(" ", "_") else: raise ValueError(f"Unsupported type {type(item)} for embedding") if namespace is None: raise ValueError( "The default namespace must be provided when embedding a string or _Embed object." # noqa: E501 ) return {namespace: keep_str + encoded}
[docs]def embed_dict_type(item: Dict, model: Any) -> Dict[str, Any]: """Embed a dictionary item.""" inner_dict: Dict = {} for ns, embed_item in item.items(): if isinstance(embed_item, list): inner_dict[ns] = [] for embed_list_item in embed_item: embedded = embed_string_type(embed_list_item, model, ns) inner_dict[ns].append(embedded[ns]) else: inner_dict.update(embed_string_type(embed_item, model, ns)) return inner_dict
[docs]def embed_list_type( item: list, model: Any, namespace: Optional[str] = None ) -> List[Dict[str, Union[str, List[str]]]]: """Embed a list item.""" ret_list: List = [] for embed_item in item: if isinstance(embed_item, dict): ret_list.append(embed_dict_type(embed_item, model)) elif isinstance(embed_item, list): item_embedding = embed_list_type(embed_item, model, namespace) # Get the first key from the first dictionary first_key = next(iter(item_embedding[0])) # Group the values under that key grouping = {first_key: [item[first_key] for item in item_embedding]} ret_list.append(grouping) else: ret_list.append(embed_string_type(embed_item, model, namespace)) return ret_list
[docs]def embed( to_embed: Union[Union[str, _Embed], Dict, List[Union[str, _Embed]], List[Dict]], model: Any, namespace: Optional[str] = None, ) -> List[Dict[str, Union[str, List[str]]]]: """ Embed the actions or context using the SentenceTransformer model (or a model that has an `encode` function). Attributes: to_embed: (Union[Union(str, _Embed(str)), Dict, List[Union(str, _Embed(str))], List[Dict]], required) The text to be embedded, either a string, a list of strings or a dictionary or a list of dictionaries. namespace: (str, optional) The default namespace to use when dictionary or list of dictionaries not provided. model: (Any, required) The model to use for embedding Returns: List[Dict[str, str]]: A list of dictionaries where each dictionary has the namespace as the key and the embedded string as the value """ # noqa: E501 if (isinstance(to_embed, _Embed) and isinstance(to_embed.value, str)) or isinstance( to_embed, str ): return [embed_string_type(to_embed, model, namespace)] elif isinstance(to_embed, dict): return [embed_dict_type(to_embed, model)] elif isinstance(to_embed, list): return embed_list_type(to_embed, model, namespace) else: raise ValueError("Invalid input format for embedding")