TypeError: read_hdf () takes exactly 2 arguments (1 given)

Question

How to open a HDF5 file using pandas.read_hdf when the keys are not known?

 from pandas.io.pytables import read_hdf read_hdf(path_or_buf, key) pandas.__version__ == '0.14.1' 

Here the key parameter is unknown. Thanks

Answer 1

Never working with hdf files before I could use online docs to prepare an example:

 In [59]: # create a temp df and store it df_tl = pd.DataFrame(dict(A=list(range(5)), B=list(range(5)))) df_tl.to_hdf('store_tl.h5','table',append=True) In [60]: # we can simply read it again and the keys are displayed store = pd.HDFStore('store_tl.h5') # keys will be displayed in the output store Out[60]: <class 'pandas.io.pytables.HDFStore'> File path: store_tl.h5 /table frame_table (typ->appendable,nrows->5,ncols->2,indexers->[index]) In [61]: # read it back in again t = pd.read_hdf('store_tl.h5', 'table') t Out[61]: AB 0 0 0 1 1 1 2 2 2 3 3 3 4 4 4 

So, just load it using HDFStore and pass the path, and then just show that the object will print the keys on the output.

Answer 2

Or you could just do store.keys()

https://github.com/pydata/pandas/blob/master/pandas/io/pytables.py#L492