[Feature]: Output logps of given output

[lycheeyolo]

🚀 The feature, motivation and pitch

vllm is a great project. and i have meet the problem that how could i acquire the logps of a given input and output?
for example, when the question is "who are you?", i want acquire the logps of answer "i am GPT model". i could not find any functions to realize this issue.

Alternatives

No response

Additional context

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[DarkLight1337]

You can pass sampling_params=SamplingParams(prompt_logprobs=...) for offline inference. A corresponding option is also available for online inference, please read the docs.

[lycheeyolo]

it seems like not fit this problem. when i ask the LLM that "who are you?", i want it output the logps of the answer "i am GPT model". and the "i am GPT model" what i expected.
what is expected may be a function like:
def get_logps(question, answer):
return logps

or may you explain more about your methods?

[DarkLight1337]

You can also pass logprobs argument. See this page.