.. sectionauthor:: Duncan Macleod <duncan.macleod@ligo.org>

.. currentmodule:: gwpy.table.lsctables

Plotting an event table in a scatter
####################################

I would like to study the event triggers generated by the `ExcessPower <link>`_
gravitational-wave burst detection algorithm, over a small stretch of data.

The data from which these events were generated are a simulation of Gaussian noise
with the Advanced LIGO design spectrum, and so don't actually contain any real
gravitational waves, but will help tune the algorithm to improve detection of
future, real signals.



First, we import the `SnglBurstTable`

.. code-block:: python

   from gwpy.table.lsctables import SnglBurstTable


and read a set of events

.. code-block:: python

   events = SnglBurstTable.read('../../gwpy/tests/data/H1-LDAS_STRAIN-968654552-10.xml.gz')


We can now make a scatter plot by specifying the x- and y-axis columns, and (optionally) the colour:

.. code-block:: python

   plot = events.plot('time', 'central_freq', color='snr', edgecolor='none', epoch=968654552)
   plot.set_xlim(968654552, 968654552+10)
   plot.set_ylabel('Frequency [Hz]')
   plot.set_yscale('log')
   plot.set_title('LIGO Hanford Observatory event triggers for GW100916')
   plot.add_colorbar(clim=[1, 5], label='Signal-to-noise ratio', cmap='hot_r')
   plot.show()

.. plot:: ../examples/table/scatter.py