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

.. currentmodule:: gwpy.frequencyseries

Calculating and plotting a `SpectralVariance` histogram
#######################################################



In order to generate a `SpectralVariance` histogram we need to import the
`~gwpy.timeseries.TimeSeries` and :meth:`~gwpy.timeseries.TimeSeries.get`
the data:

.. code-block:: python

   from gwpy.timeseries import TimeSeries
   llo = TimeSeries.get(
       'L1:LDAS-STRAIN,rds', 'August 1 2010', 'August 1 2010 00:10')


We can then call the :meth:`~gwpy.timeseries.TimeSeries.spectral_variance`
method of the ``llo`` `~gwpy.timeseries.TimeSeries`:

.. code-block:: python

   variance = llo.spectral_variance(1, log=True, low=1e-24, high=1e-19, nbins=100)


We can then :meth:`~SpectralVariance.plot` the `SpectralVariance`

.. code-block:: python

   plot = variance.plot(norm='log', vmin=0.5, vmax=100)
   ax = plot.gca()
   ax.grid()
   ax.set_xlim(40, 4096)
   ax.set_ylim(1e-24, 1e-19)
   ax.set_xlabel('Frequency [Hz]')
   ax.set_ylabel(r'GW ASD [strain/\rtHz]')
   ax.set_title('LIGO Livingston Observatory sensitivity variance')
   plot.show()

.. plot:: ../examples/frequencyseries/variance.py