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Confusion Over `run_experiment` Function Arguments in Phoenix Client | Arize AI Community

Phoenix Support

Confusion Over `run_experiment` Function Arguments in Phoenix Client

·Aug 11, 2025 05:02 PM

a bit confused by reading https://github.com/Arize-ai/phoenix/blob/28d56f691a27136f0a4dc82c0efe27c6b7de1c79/packages/phoenix-client/src/phoenix/client/experiments/__init__.py#L115-L116, does `run_experiment really take base_url , which is not in the arg list, https://github.com/Arize-ai/phoenix/blob/28d56f691a27136f0a4dc82c0efe27c6b7de1c79/packages/phoenix-client/src/phoenix/client/experiments/__init__.py#L17-L30, am I missing something obvious?

4 comments

· Sorted by Oldest

RunLLM
APP
·
You are correct: the run_experiment function in phoenix.client.experiments.__init__.py does not take base_url as a direct argument in its signature (see here). Instead, base_url is used when you instantiate a Client, which you can then pass to run_experiment via the client argument. The function itself only accepts client, not base_url directly.If you want to specify a custom base_url, you should create a Client with that base_url and pass the client to run_experiment. Passing base_url directly to run_experiment will not work, as it is not a recognized parameter in the function signature (source).Would you like a code example or more detail on how to use a custom base_url with run_experiment?Sources: - see here
💡 Hint: Mention RunLLM in the thread for followups.
Zhuyi X.
·
Does that mean the examples in the docstring is wrong?
Zhuyi X.
·
we'd prefer the flexibility of setting base_url, I recall the previous api at phoenix.experiments.run_experiment won't allow it (it only reads from env var). this new api seems to allow it by passing client explicitly, but the docstring appears wrong.
Zhuyi X.
·
Does passing client explicitly work for you?
yeah, it should work. I'll try it out later.
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