"This creates an HDF5 file with a potentially large number of objects"

import sys

import numpy as np

import tables as tb

filename = sys.argv[1]

# Open a new empty HDF5 file
fileh = tb.open_file(filename, mode="w")

# nlevels -- Number of levels in hierarchy
# ngroups -- Number of groups on each level
# ndatasets -- Number of arrays on each group
# LR: Low ratio groups/datasets
# nlevels, ngroups, ndatasets = (3, 1, 1000)
# MR: Medium ratio groups/datasets
nlevels, ngroups, ndatasets = (3, 10, 100)
# nlevels, ngroups, ndatasets = (3, 5, 10)
# HR: High ratio groups/datasets
# nlevels, ngroups, ndatasets = (30, 10, 10)

# Create an Array to save on disk
a = np.array([-1, 2, 4], np.int16)

group = fileh.root
group2 = fileh.root
for k in range(nlevels):
    for j in range(ngroups):
        for i in range(ndatasets):
            # Save the array on the HDF5 file
            fileh.create_array(
                group2, "array" + str(i), a, "Signed short array"
            )
        # Create a new group
        group2 = fileh.create_group(group, "group" + str(j))
    # Create a new group
    group3 = fileh.create_group(group, "ngroup" + str(k))
    # Iterate over this new group (group3)
    group = group3
    group2 = group3

fileh.close()