md_trajectory = nlread('sio2.nc')[-1]

q_number = QNumbers(
    md_trajectory,
    element_selection=[Oxygen, Silicon, Oxygen],
    fuzz_factor=1.2,
    calculate_distribution=True,
)

# Get the histogram and the associated the coordination numbers.
bin_edges = q_number.qNumbers() - 0.4
histogram = q_number.data()

# Plot the data using pylab.
import pylab

pylab.bar(bin_edges, histogram, label='O-Si-O', width=0.8)
pylab.xlabel('Q-number')
pylab.ylabel('Histogram')
pylab.legend()

pylab.show()