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82 lines
2.3 KiB
Python
82 lines
2.3 KiB
Python
"""Chain that just formats a prompt and calls an LLM."""
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from typing import Any, Dict, List
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from pydantic import BaseModel, Extra
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from langchain.chains.base import Chain
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from langchain.printing import print_text
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from langchain.llms.base import LLM
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from langchain.prompts.base import BasePromptTemplate
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from langchain.logger import CONTEXT_KEY
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class LLMChain(Chain, BaseModel):
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"""Chain to run queries against LLMs.
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Example:
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.. code-block:: python
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from langchain import LLMChain, OpenAI, PromptTemplate
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prompt_template = "Tell me a {adjective} joke"
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prompt = PromptTemplate(
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input_variables=["adjective"], template=prompt_template
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)
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llm = LLMChain(llm=OpenAI(), prompt=prompt)
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"""
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prompt: BasePromptTemplate
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"""Prompt object to use."""
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llm: LLM
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"""LLM wrapper to use."""
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output_key: str = "text" #: :meta private:
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class Config:
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"""Configuration for this pydantic object."""
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extra = Extra.forbid
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arbitrary_types_allowed = True
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@property
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def input_keys(self) -> List[str]:
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"""Will be whatever keys the prompt expects.
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:meta private:
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"""
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return self.prompt.input_variables
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@property
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def output_keys(self) -> List[str]:
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"""Will always return text key.
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:meta private:
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"""
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return [self.output_key]
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def _call(self, inputs: Dict[str, Any]) -> Dict[str, str]:
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selected_inputs = {k: inputs[k] for k in self.prompt.input_variables}
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prompt = self.prompt.format(**selected_inputs)
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if self.logger:
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title="Prompt after formatting:"
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self.logger.log(prompt, inputs[CONTEXT_KEY],title=title, color="green", end="\n")
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kwargs = {}
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if "stop" in inputs:
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kwargs["stop"] = inputs["stop"]
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response = self.llm(prompt, **kwargs)
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return {self.output_key: response}
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def predict(self, **kwargs: Any) -> str:
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"""Format prompt with kwargs and pass to LLM.
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Args:
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**kwargs: Keys to pass to prompt template.
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Returns:
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Completion from LLM.
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Example:
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.. code-block:: python
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completion = llm.predict(adjective="funny")
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"""
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return self(kwargs)[self.output_key]
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