Write pandas DataFrame to HDF in memory buffer

Question

I want to get a dataframe as hdf in memory. The code below results in "AttributeError: '_io.BytesIO' object has no attribute 'put'". I am using python 3.5 and pandas 0.17

import pandas as pd
import numpy as np
import io

df = pd.DataFrame(np.arange(8).reshape(-1, 2), columns=['a', 'b'])
buf = io.BytesIO()
df.to_hdf(buf, 'some_key')

Update: As UpSampler pointed out "path_or_buf" cannot be an io stream (which I find confusing since buf usually can be an io stream, see to_csv). Other than writing to disk and reading it back in, can I get a dataframe as hdf in memory?

Answer 1

Your first argument to df.to_hdf() has to be a "path (string) or HDFStore object" not an io stream. Documentation: http://pandas.pydata.org/pandas-docs/version/0.17.0/generated/pandas.DataFrame.to_hdf.html