FEATURE: Relative Binning in bilby

See merge request lscsoft/bilby!1105

Author: ColmTalbot

AUTHORS.md

@@ -9,6 +9,7 @@ Aditya Vijaykumar
 Andrew Kim
 Andrew Miller
 Antoni Ramos-Buades
+Apratim Ganguly
 Avi Vajpeyi
 Bruce Edelman
 Carl-Johan Haster
@@ -40,6 +41,7 @@ Karl Wette
 Katerina Chatziioannou
 Kaylee de Soto
 Khun Sang Phukon
+Kruthi Krishna
 Kshipraa Athar
 Leslie Wade
 Liting Xiao

bilby/gw/conversion.py

@@ -1407,11 +1407,9 @@ def compute_snrs(sample, likelihood, npool=1):
     if likelihood is not None:
         if isinstance(sample, dict):
             likelihood.parameters.update(sample)
-            signal_polarizations =\
-                likelihood.waveform_generator.frequency_domain_strain(sample)
+            signal_polarizations = likelihood.waveform_generator.frequency_domain_strain(sample)
             for ifo in likelihood.interferometers:
-                per_detector_snr = likelihood.calculate_snrs(
-                    signal_polarizations, ifo)
+                per_detector_snr = likelihood.calculate_snrs(signal_polarizations, ifo)
                 sample['{}_matched_filter_snr'.format(ifo.name)] =\
                     per_detector_snr.complex_matched_filter_snr
                 sample['{}_optimal_snr'.format(ifo.name)] = \

bilby/gw/detector/interferometer.py

@@ -285,7 +285,7 @@ def antenna_response(self, ra, dec, time, psi, mode):
         else:
             return 0
 
-    def get_detector_response(self, waveform_polarizations, parameters):
+    def get_detector_response(self, waveform_polarizations, parameters, frequencies=None):
         """ Get the detector response for a particular waveform
 
         Parameters
@@ -294,11 +294,21 @@ def get_detector_response(self, waveform_polarizations, parameters):
             polarizations of the waveform
         parameters: dict
             parameters describing position and time of arrival of the signal
-
+        frequencies: array-like, optional
+        The frequency values to evaluate the response at. If
+        not provided, the response is computed using
+        :code:`self.frequency_array`. If the frequencies are
+        specified, no frequency masking is performed.
         Returns
         =======
         array_like: A 3x3 array representation of the detector response (signal observed in the interferometer)
         """
+        if frequencies is None:
+            frequencies = self.frequency_array[self.frequency_mask]
+            mask = self.frequency_mask
+        else:
+            mask = np.ones(len(frequencies), dtype=bool)
+
         signal = {}
         for mode in waveform_polarizations.keys():
             det_response = self.antenna_response(
@@ -308,9 +318,7 @@ def get_detector_response(self, waveform_polarizations, parameters):
                 parameters['psi'], mode)
 
             signal[mode] = waveform_polarizations[mode] * det_response
-        signal_ifo = sum(signal.values())
-
-        signal_ifo *= self.strain_data.frequency_mask
+        signal_ifo = sum(signal.values()) * mask
 
         time_shift = self.time_delay_from_geocenter(
             parameters['ra'], parameters['dec'], parameters['geocent_time'])
@@ -320,12 +328,11 @@ def get_detector_response(self, waveform_polarizations, parameters):
         dt_geocent = parameters['geocent_time'] - self.strain_data.start_time
         dt = dt_geocent + time_shift
 
-        signal_ifo[self.strain_data.frequency_mask] = signal_ifo[self.strain_data.frequency_mask] * np.exp(
-            -1j * 2 * np.pi * dt * self.strain_data.frequency_array[self.strain_data.frequency_mask])
+        signal_ifo[mask] = signal_ifo[mask] * np.exp(-1j * 2 * np.pi * dt * frequencies)
 
-        signal_ifo[self.strain_data.frequency_mask] *= self.calibration_model.get_calibration_factor(
-            self.strain_data.frequency_array[self.strain_data.frequency_mask],
-            prefix='recalib_{}_'.format(self.name), **parameters)
+        signal_ifo[mask] *= self.calibration_model.get_calibration_factor(
+            frequencies, prefix='recalib_{}_'.format(self.name), **parameters
+        )
 
         return signal_ifo
 

bilby/gw/likelihood/__init__.py

@@ -2,6 +2,7 @@
 from .basic import BasicGravitationalWaveTransient
 from .roq import BilbyROQParamsRangeError, ROQGravitationalWaveTransient
 from .multiband import MBGravitationalWaveTransient
+from .relative import RelativeBinningGravitationalWaveTransient
 
 from ..source import lal_binary_black_hole
 from ..waveform_generator import WaveformGenerator

bilby/gw/likelihood/base.py

@@ -265,8 +265,10 @@ def calculate_snrs(self, waveform_polarizations, interferometer):
             The bilby interferometer object
 
         """
-        signal = interferometer.get_detector_response(
-            waveform_polarizations, self.parameters)
+        signal = self._compute_full_waveform(
+            signal_polarizations=waveform_polarizations,
+            interferometer=interferometer,
+        )
         _mask = interferometer.frequency_mask
 
         if 'recalib_index' in self.parameters:
@@ -614,8 +616,10 @@ def generate_time_sample_from_marginalized_likelihood(
         for ifo in self.interferometers:
             ifo_length = len(ifo.frequency_domain_strain)
             mask = ifo.frequency_mask
-            signal = ifo.get_detector_response(
-                signal_polarizations, self.parameters)
+            signal = self._compute_full_waveform(
+                signal_polarizations=signal_polarizations,
+                interferometer=ifo,
+            )
             signal_long[:ifo_length] = signal
             data[:ifo_length] = np.conj(ifo.frequency_domain_strain)
             psd[:ifo_length][mask] = ifo.power_spectral_density_array[mask]
@@ -703,6 +707,23 @@ def _calculate_inner_products(self, signal_polarizations):
             h_inner_h += per_detector_snr.optimal_snr_squared
         return d_inner_h, h_inner_h
 
+    def _compute_full_waveform(self, signal_polarizations, interferometer):
+        """
+        Project the waveform polarizations against the interferometer
+        response. This is useful for likelihood classes that don't
+        use the full frequency array, e.g., the relative binning
+        likelihood.
+
+        Parameters
+        ==========
+        signal_polarizations: dict
+            Dictionary containing the waveform evaluated at
+            :code:`interferometer.frequency_array`.
+        interferometer: bilby.gw.detector.Interferometer
+            Interferometer to compute the response with respect to.
+        """
+        return interferometer.get_detector_response(signal_polarizations, self.parameters)
+
     def generate_phase_sample_from_marginalized_likelihood(
             self, signal_polarizations=None):
         r"""