rank_stat_single was not using KDE or BBH weighting - bugfix (gwastro…

…#4499)

* Fix a bug where the KDE weighting was not applied to the single-detector ranking statistic

* BBH weighting factor for singles

* add docstring

* CC

* rename function

pycbc/events/stat.py

@@ -1733,6 +1733,32 @@ def logsignalrate(self, stats, shift, to_shift):
         logr_s += numpy.log((self.curr_mchirp / 20.) ** (11. / 3.))
         return logr_s
 
+    def rank_stat_single(self, single_info,
+                         **kwargs): # pylint:disable=unused-argument
+        """
+        Calculate the statistic for a single detector candidate
+
+        This calls back to the Parent class and then applies the chirp mass
+        weighting factor.
+
+        Parameters
+        ----------
+        single_info: tuple
+            Tuple containing two values. The first is the ifo (str) and the
+            second is the single detector triggers.
+
+        Returns
+        -------
+        numpy.ndarray
+            The array of single detector statistics
+        """
+        rank_sngl = ExpFitFgBgNormStatistic.rank_stat_single(
+            self,
+            single_info,
+            **kwargs)
+        rank_sngl += numpy.log((self.curr_mchirp / 20.) ** (11. / 3.))
+        return rank_sngl
+
     def single(self, trigs):
         """
         Calculate the necessary single detector information
@@ -1847,6 +1873,16 @@ def assign_kdes(self, kname):
         with h5py.File(self.files[kname + '-kde_file'], 'r') as kde_file:
             self.kde_by_tid[kname + '_kdevals'] = kde_file['data_kde'][:]
 
+    def kde_ratio(self):
+        """
+        Calculate the weighting factor according to the ratio of the
+        signal and template KDE lookup tables
+        """
+        signal_kde = self.kde_by_tid["signal_kdevals"][self.curr_tnum]
+        template_kde = self.kde_by_tid["template_kdevals"][self.curr_tnum]
+
+        return numpy.log(signal_kde / template_kde)
+
     def logsignalrate(self, stats, shift, to_shift):
         """
         Calculate the normalized log rate density of signals via lookup.
@@ -1870,11 +1906,33 @@ def logsignalrate(self, stats, shift, to_shift):
         """
         logr_s = ExpFitFgBgNormStatistic.logsignalrate(self, stats, shift,
                                                        to_shift)
-        signal_kde = self.kde_by_tid["signal_kdevals"][self.curr_tnum]
-        template_kde = self.kde_by_tid["template_kdevals"][self.curr_tnum]
-        logr_s += numpy.log(signal_kde / template_kde)
+        logr_s += self.kde_ratio()
+
         return logr_s
 
+    def rank_stat_single(self, single_info,
+                         **kwargs): # pylint:disable=unused-argument
+        """
+        Calculate the statistic for a single detector candidate
+
+        Parameters
+        ----------
+        single_info: tuple
+            Tuple containing two values. The first is the ifo (str) and the
+            second is the single detector triggers.
+
+        Returns
+        -------
+        numpy.ndarray
+            The array of single detector statistics
+        """
+        rank_sngl = ExpFitFgBgNormStatistic.rank_stat_single(
+            self,
+            single_info,
+            **kwargs)
+        rank_sngl += self.kde_ratio()
+        return rank_sngl
+
     def coinc_lim_for_thresh(self, s, thresh, limifo, **kwargs):
         """
         Optimization function to identify coincs too quiet to be of interest
@@ -2082,13 +2140,29 @@ def __init__(self, sngl_ranking, files=None, ifos=None, **kwargs):
         for kname in self.kde_names:
             ExpFitFgBgKDEStatistic.assign_kdes(self, kname)
 
+    def kde_ratio(self):
+        """
+        Inherited, see docstring for ExpFitFgBgKDEStatistic.kde_signalrate
+        """
+        return ExpFitFgBgKDEStatistic.kde_ratio(self)
+
     def logsignalrate(self, stats, shift, to_shift):
         """
         Inherited, see docstring for ExpFitFgBgKDEStatistic.logsignalrate
         """
         return ExpFitFgBgKDEStatistic.logsignalrate(self, stats, shift,
                                                     to_shift)
 
+    def rank_stat_single(self, single_info,
+                         **kwargs): # pylint:disable=unused-argument
+        """
+        Inherited, see docstring for ExpFitFgBgKDEStatistic.rank_stat_single
+        """
+        return ExpFitFgBgKDEStatistic.rank_stat_single(
+            self,
+            single_info,
+            **kwargs)
+
     def coinc_lim_for_thresh(self, s, thresh, limifo, **kwargs):
         """
         Inherited, see docstring for