Error when using `format="polars"` to fetch runs histories

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1

Hey, I’m quite new to wand and I was attempting to fetch all the runs’ histories to post-process them manually via polars. Here is what I did:

api = wandb.Api()
filters = {"config.epochs": 300}
runs = api.runs(
    "<entity>/<project>",
    per_page=200,
    order="-created_at",
    filters=filters,
)
df = runs.histories(keys=["_step", "acc", "loss"], format="polars")

However this returned an unexpected error:

SchemaError: type Int64 is incompatible with expected type Float64

During handling of the above exception, another exception occurred:

CommError: type Int64 is incompatible with expected type Float64

but this line works fine (albeit slow): runs.histories(keys=["_step", "acc", "loss"], format="pandas"), returning all the runs’ histories with 4 columns: _step, acc, loss, and run_id.

I’m assuming it’s due to polars internally requiring strict datatype matching when concatenating records.