Add LightCurve class

examples/example_lightcurve.py

@@ -0,0 +1,7 @@
+### Using the Lightcurve class
+from gammapy.time import LightCurve, make_example_lightcurve
+
+lc = make_example_lightcurve()
+print('the mean flux is {}'.format(lc['FLUX'].mean()))
+print('the std dev of the flux is {}'.format(lc['FLUX'].std()))
+lc.lc_plot()

gammapy/time/__init__.py

@@ -5,3 +5,4 @@
 from .plot import *
 from .simulate import *
 from .utils import *
+from .lightcurve import *

gammapy/time/lightcurve.py

@@ -0,0 +1,59 @@
+# Licensed under a 3-clause BSD style license - see LICENSE.rst
+"""
+Lightcurve and elementary temporal functions
+"""
+from astropy.table import Table
+from astropy.table import QTable
+from astropy.units import Quantity
+import astropy.units as u
+
+
+__all__ = [
+    'LightCurve',
+    'make_example_lightcurve',
+]
+
+
+class LightCurve(QTable):
+    """LightCurve class.
+
+    Contains all data in the tabular form with columns 
+    tstart, tstop, flux, flux error, time bin (opt). 
+    Possesses functions allowing plotting data, saving as txt 
+    and elementary stats like mean & std dev.
+
+    to do: specification of format is work in progress ; will add link
+    """
+
+#    def __init__(self, table):
+#	super(LightCurve,self).__init__(table)    
+
+    def lc_plot(self):
+        """Plots the Lightcurve. 
+
+        The flux as a function of time.
+        Here, time for each bin is equal to the center of the bin, 
+        i.e. the average of tstart and tstop	 
+        """
+        import matplotlib.pyplot as plt
+        tstart = self['TIME_MIN'].to('s')
+        tstop = self['TIME_MAX'].to('s')
+        time = (tstart + tstop) / 2.0
+        flux = self['FLUX'].to('cm-2 s-1')
+        errors = self['FLUX_ERR'].to('cm-2 s-1')
+        plt.errorbar(time.value, flux.value,
+                     yerr=errors.value, linestyle="None")
+        plt.scatter(time, flux)
+        plt.xlabel("Time (secs)")
+        plt.ylabel("Flux ($cm^{-2} sec^{-1}$)")
+        plt.title("Lightcurve")
+
+def make_example_lightcurve():
+    """ Make an example lightcurve.
+    """
+    lc = LightCurve()
+    lc['TIME_MIN'] = [1, 4, 7, 9] * u.s
+    lc['TIME_MAX'] = [1, 4, 7, 9] * u.s
+    lc['FLUX'] = Quantity([1, 4, 7, 9], 'cm^-2 s^-1')
+    lc['FLUX_ERR'] = Quantity([0.1, 0.4, 0.7, 0.9], 'cm^-2 s^-1')
+    return lc

gammapy/time/tests/test_lightcurve.py

@@ -0,0 +1,16 @@
+# Licensed under a 3-clause BSD style license - see LICENSE.rst
+from __future__ import absolute_import, division, print_function, unicode_literals
+from numpy.testing import assert_almost_equal
+from astropy.units import Quantity
+from astropy.tests.helper import assert_quantity_allclose
+from ..lightcurve import LightCurve, make_example_lightcurve
+
+
+def test_lightcurve():
+    lc = make_example_lightcurve()	
+    flux_mean = lc['FLUX'].mean() 
+    assert_quantity_allclose(flux_mean, Quantity(5.25,'cm^-2 s^-1'))
+
+def test_lightcurve_plot():
+    lc = make_example_lightcurve()	
+    lc.lc_plot()