Matplotlib

Plotting via matplotlib

The genie_python distribution of python includes a powerful plotting library called matplotlib.

Matplotlib is a highly customizable, general purpose plotting library capable of producing a wide variety of plot types. There are lots of tutorials and examples online, such as:

• matplotlib.pyplot API reference
• Matplotlib tutorials
• Matplotlib examples

Quick-start

To import pyplot

import matplotlib.pyplot as pyplot

To create (and show) an example plot

pyplot.plot(range(10))
pyplot.show()

To remove all plots and start with a completely clean matplotlib screen.

pyplot.close('all')

To plot a constantly-updating sin wave

from math import sin
from time import time, sleep
pyplot.show()
while True:
    pyplot.clf()
    pyplot.plot([sin(x/1000.0 + time()) for x in range(10000)])
    pyplot.draw()
    sleep(0.05)

Plotting spectra

The genie_python library includes commands to quickly plot the neutron spectra on an instrument.

Plot a single spectrum:

g.plot_spectrum(1)

Plot several spectra on one graph:

graph = g.plot_spectrum(1)
graph.add_spectrum(2)
graph.add_spectrum(3, period=2)

For greater control over the exact presentation or contents of the spectra plots, the raw spectrum data can be acquired using:

g.get_spectrum(spectrum=1)

Using matplotlib within the IBEX GUI

The IBEX user interface includes a python scripting window. When plotting graphs within IBEX, matplotlib is configured to display the plot within the IBEX gui.

In the IBEX user interface, matplotlib is non-blocking - that is, a script will continue once a plot has been drawn without the plot needing to be closed.

Note: this is new functionality as of July 2018. If you prefer matplotlib windows to spawn separately from the main IBEX window, you can type the matplotlib command:

matplotlib.use('Qt4Agg')

This needs to be typed before any matplotlib functionality is used for it to take effect.