```python from langchain import PromptTemplate, OpenAI, LLMChain prompt_template = "What is a good name for a company that makes {product}?" llm = OpenAI(temperature=0) llm_chain = LLMChain( llm=llm, prompt=PromptTemplate.from_template(prompt_template) ) llm_chain("colorful socks") ``` ``` {'product': 'colorful socks', 'text': '\n\nSocktastic!'} ``` ## Additional ways of running LLM Chain Aside from `__call__` and `run` methods shared by all `Chain` object, `LLMChain` offers a few more ways of calling the chain logic: - `apply` allows you run the chain against a list of inputs: ```python input_list = [ {"product": "socks"}, {"product": "computer"}, {"product": "shoes"} ] llm_chain.apply(input_list) ``` ``` [{'text': '\n\nSocktastic!'}, {'text': '\n\nTechCore Solutions.'}, {'text': '\n\nFootwear Factory.'}] ``` - `generate` is similar to `apply`, except it return an `LLMResult` instead of string. `LLMResult` often contains useful generation such as token usages and finish reason. ```python llm_chain.generate(input_list) ``` ``` LLMResult(generations=[[Generation(text='\n\nSocktastic!', generation_info={'finish_reason': 'stop', 'logprobs': None})], [Generation(text='\n\nTechCore Solutions.', generation_info={'finish_reason': 'stop', 'logprobs': None})], [Generation(text='\n\nFootwear Factory.', generation_info={'finish_reason': 'stop', 'logprobs': None})]], llm_output={'token_usage': {'prompt_tokens': 36, 'total_tokens': 55, 'completion_tokens': 19}, 'model_name': 'text-davinci-003'}) ``` - `predict` is similar to `run` method except that the input keys are specified as keyword arguments instead of a Python dict. ```python # Single input example llm_chain.predict(product="colorful socks") ``` ``` '\n\nSocktastic!' ``` ```python # Multiple inputs example template = """Tell me a {adjective} joke about {subject}.""" prompt = PromptTemplate(template=template, input_variables=["adjective", "subject"]) llm_chain = LLMChain(prompt=prompt, llm=OpenAI(temperature=0)) llm_chain.predict(adjective="sad", subject="ducks") ``` ``` '\n\nQ: What did the duck say when his friend died?\nA: Quack, quack, goodbye.' ``` ## Parsing the outputs By default, `LLMChain` does not parse the output even if the underlying `prompt` object has an output parser. If you would like to apply that output parser on the LLM output, use `predict_and_parse` instead of `predict` and `apply_and_parse` instead of `apply`. With `predict`: ```python from langchain.output_parsers import CommaSeparatedListOutputParser output_parser = CommaSeparatedListOutputParser() template = """List all the colors in a rainbow""" prompt = PromptTemplate(template=template, input_variables=[], output_parser=output_parser) llm_chain = LLMChain(prompt=prompt, llm=llm) llm_chain.predict() ``` ``` '\n\nRed, orange, yellow, green, blue, indigo, violet' ``` With `predict_and_parse`: ```python llm_chain.predict_and_parse() ``` ``` ['Red', 'orange', 'yellow', 'green', 'blue', 'indigo', 'violet'] ``` ## Initialize from string You can also construct an LLMChain from a string template directly. ```python template = """Tell me a {adjective} joke about {subject}.""" llm_chain = LLMChain.from_string(llm=llm, template=template) ``` ```python llm_chain.predict(adjective="sad", subject="ducks") ``` ``` '\n\nQ: What did the duck say when his friend died?\nA: Quack, quack, goodbye.' ```