#! /usr/bin/env python

import h5py
import numpy

class HFile(object):
    def __init__(self, name, mode="w"):
        self.f = h5py.File(name, mode)
        self.attrs = self.f.attrs

    def __setitem__(self, name, data):
        if not name in self.f:
            self.f.create_dataset(name, data=data, compression="gzip",
                                  compression_opts=9, shuffle=True,
                                  maxshape=data.shape)
        else:
            self.f[name].resize(data.shape)
            self.f[name][:] = data

    def __getitem__(self, *args):
        return self.f.__getitem__(*args)

    def close(self):
        self.f.close()

# open file
fp = HFile("test.hdf", "w")
dataset_name = "test_arr/0"

# create some data that has 100 elements
data_100 = numpy.arange(0, 100)

# create some data that has 95 elements
data_95 = numpy.arange(95 - 1, 0 - 1, -1)

# create a dataset
# use maxshape to resize datasets
fp[dataset_name] = data_100
print fp[dataset_name][:]

# resize to smaller array shape
fp[dataset_name] = data_95
print fp[dataset_name][:]

# close
fp.close()