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add from string method (#820)

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Harrison Chase 2023-02-02 08:23:54 -08:00 committed by GitHub
parent ba26a879e0
commit 3f952eb597
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1 changed files with 13 additions and 0 deletions
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13
langchain/chains/llm.py
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@ -1,4 +1,5 @@
"""Chain that just formats a prompt and calls an LLM.""" """Chain that just formats a prompt and calls an LLM."""
from string import Formatter
from typing import Any, Dict, List, Sequence, Union from typing import Any, Dict, List, Sequence, Union
from pydantic import BaseModel, Extra from pydantic import BaseModel, Extra
@ -7,6 +8,7 @@ from langchain.chains.base import Chain
from langchain.input import get_colored_text from langchain.input import get_colored_text
from langchain.llms.base import BaseLLM from langchain.llms.base import BaseLLM
from langchain.prompts.base import BasePromptTemplate from langchain.prompts.base import BasePromptTemplate
from langchain.prompts.prompt import PromptTemplate
from langchain.schema import LLMResult from langchain.schema import LLMResult
@ -126,3 +128,14 @@ class LLMChain(Chain, BaseModel):
@property @property
def _chain_type(self) -> str: def _chain_type(self) -> str:
return "llm_chain" return "llm_chain"
@classmethod
def from_string(cls, llm: BaseLLM, template: str) -> Chain:
"""Create LLMChain from LLM and template."""
input_variables = {
v for _, v, _, _ in Formatter().parse(template) if v is not None
}
prompt_template = PromptTemplate(
input_variables=list(input_variables), template=template
)
return cls(llm=llm, prompt=prompt_template)