Truncate SNR/FAR for live pastro calcs

pycbc/population/live_pastro.py

@@ -31,6 +31,27 @@ def check_template_param_bin_data(spec_json):
     return spec_json
 
 
+def check_template_param_bin_farlim_data(spec_json):
+    """
+    Parameters
+    ----------
+    spec_json: JSON dictionary-like object
+        Result of parsing json file containing static data
+
+    Returns
+    -------
+    spec_json: dictionary
+    """
+    # Standard template param bin checks
+    check_template_param_bin_data(spec_json)
+
+    # In addition, need limiting FAR and SNR values
+    assert 'limit_far' in spec_json
+    assert 'limit_snr' in spec_json
+
+    return spec_json
+
+
 def read_template_bank_param(spec_d, bankf):
     """
     Parameters
@@ -206,7 +227,7 @@ def template_param_bin_types_pa(padata, trdata, horizons):
     else:
         expfac = padata.spec['bg_fac']
 
-    # Ifos over trigger threshold
+    # List of ifos over trigger threshold
     tr_ifos = trdata['triggered']
 
     # FAR is in Hz, therefore convert to rate per year (per SNR)
@@ -238,6 +259,29 @@ def template_param_bin_types_pa(padata, trdata, horizons):
     return p_astro, 1 - p_astro
 
 
+def template_param_bin_types_farlim_pa(padata, trdata, horizons):
+    """
+    Parameters
+    ----------
+    padata: PAstroData instance
+        Static information on p astro calculation
+    trdata: dictionary
+        Trigger properties
+    horizons: dictionary
+        BNS horizon distances keyed on ifo
+
+    Returns
+    -------
+    p_astro, p_terr: tuple of floats
+    """
+    # If the network SNR and FAR indicate saturation of the FAR estimate,
+    # set them to specified fixed values
+    trdata = padata.apply_significance_limits(trdata)
+
+    # Now perform standard calculation with event types
+    return template_param_bin_types_pa(padata, trdata, horizons)
+
+
 __all__ = [
     "check_template_param_bin_data",
     "read_template_bank_param",
@@ -247,4 +291,5 @@ def template_param_bin_types_pa(padata, trdata, horizons):
     "signal_rate_trig_type",
     "template_param_bin_pa",
     "template_param_bin_types_pa",
+    "template_param_bin_types_farlim_pa",
 ]

pycbc/population/live_pastro_utils.py

@@ -27,18 +27,23 @@ def insert_live_pastro_option_group(parser):
 
 # Choices of p astro calc method
 _check_spec = {
-      'template_param_bins': livepa.check_template_param_bin_data,
-      'template_param_bins_types': livepa.check_template_param_bin_data
+    'template_param_bins': livepa.check_template_param_bin_data,
+    'template_param_bins_types': livepa.check_template_param_bin_data,
+    'template_param_bins_types_farlim':
+        livepa.check_template_param_bin_farlim_data
 }
 
 _read_bank = {
-      'template_param_bins': livepa.read_template_bank_param,
-      'template_param_bins_types': livepa.read_template_bank_param
+    'template_param_bins': livepa.read_template_bank_param,
+    'template_param_bins_types': livepa.read_template_bank_param,
+    'template_param_bins_types_farlim': livepa.read_template_bank_param
 }
 
 _do_calc = {
-      'template_param_bins': livepa.template_param_bin_pa,
-      'template_param_bins_types': livepa.template_param_bin_types_pa
+    'template_param_bins': livepa.template_param_bin_pa,
+    'template_param_bins_types': livepa.template_param_bin_types_pa,
+    'template_param_bins_types_farlim':
+        livepa.template_param_bin_types_farlim_pa
 }
 
 
@@ -71,6 +76,32 @@ def __init__(self, specfile, bank):
             self.spec = _check_spec[self.method](self.spec_json)
             self.bank = _read_bank[self.method](self.spec, bank)
 
+    def apply_significance_limits(self, trigger_data):
+        """
+        If the network SNR and FAR indicate saturation of the FAR estimate,
+        set them to the fixed values given in the specification.
+        """
+        # This only happens for double or triple events
+        if len(trigger_data['triggered']) == 1:
+            return trigger_data
+
+        if len(trigger_data['triggered']) > 1:
+            farlim = self.spec['limit_far']
+            snrlim = self.spec['limit_snr']
+            # Only do anything if FAR and SNR are beyond given limits
+            if trigger_data['far'] > farlim or \
+                    trigger_data['network_snr'] < snrlim:
+                return trigger_data
+
+            logging.debug('Truncating FAR and SNR from %f, %f to %f, %f',
+                          trigger_data['far'], trigger_data['network_snr'],
+                          farlim, snrlim)
+            trigger_data['network_snr'] = snrlim
+            trigger_data['far'] = farlim
+            return trigger_data
+
+        raise RuntimeError('Number of triggered ifos must be >0 !')
+
     def do_pastro_calc(self, trigger_data, horizons):
         """ No-op, or call the despatch dictionary to evaluate p_astro """
         if not self.do: