How can extract data from .h5 file and save it in .txt or .csv properly?

After searching a lot I couldn't find a simple way to extract data from .h5 and pass it to a data.Frame by Numpy or Pandas in order to save in .txt or .csv file.

import h5pyimport numpy as npimport pandas as pdfilename = 'D:\data.h5'f = h5py.File(filename, 'r')# List all groupsprint("Keys: %s" % f.keys())a_group_key = list(f.keys())[0]# Get the datadata = list(f[a_group_key])pd.DataFrame(data).to_csv("hi.csv")

Keys: <KeysViewHDF5 ['dd48']>

When I print data I see following results:

print(data)

['axis0','axis1','block0_items','block0_values','block1_items','block1_values']

I would appreciate the if someone explain me what are they and how I can extract data completely and save it in .csv file. It seems there hasn't been a routine way to do that and it's kind of challenging yet! Until now I just could see part of data via:

import numpy as np dfm = np.fromfile('D:\data.h5', dtype=float)print (dfm.shape)print(dfm[5:])dfm=pd.to_csv('train.csv')#dfm.to_csv('hi.csv', sep=',', header=None, index=None)

My expectation is to extract time_stamps and measurements in .h5 file.