Comment by irthomasthomas

    import openai, math, os, textwrap, json, sys
    query = 'Paris is the capital of'  # short demo input
    os.environ['OPENAI_API_KEY']       # check key early
    client = openai.OpenAI()
    resp = client.chat.completions.create(
        model='gpt-3.5-turbo',
        messages=[{'role': 'user', 'content': query}],
        max_tokens=12,
        logprobs=True,
        top_logprobs=1
    )

    logprobs = [t.logprob for t in resp.choices[0].logprobs.content]
    perplexity = math.exp(-sum(logprobs) / len(logprobs))
    print('Prompt: "', query, '"', sep='')
    print('\nCompletion:', resp.choices[0].message.content)
    print('\nToken count:', len(logprobs))
    print('Perplexity:', round(perplexity, 2))

Output:

    Prompt: "Paris is the capital of"
    
    Completion:  France.
    
    Token count: 2
    Perplexity: 1.17

Meta: Out of three models: k2, qwen3-coder and opus4, only opus one-shot the correct formatting for this comment.