Source code for pycbc.vetoes.bank_chisq

# Copyright (C) 2013  Ian Harry, Alex Nitz
# This program is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation; either version 3 of the License, or (at your
# option) any later version.
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# Public License for more details.
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

# =============================================================================
#                                   Preamble
# =============================================================================
import logging, numpy
from pycbc.types import Array, zeros, real_same_precision_as, TimeSeries
from pycbc.filter import overlap_cplx, matched_filter_core
from pycbc.waveform import FilterBank
from math import sqrt

[docs]def segment_snrs(filters, stilde, psd, low_frequency_cutoff): """ This functions calculates the snr of each bank veto template against the segment Parameters ---------- filters: list of FrequencySeries The list of bank veto templates filters. stilde: FrequencySeries The current segment of data. psd: FrequencySeries low_frequency_cutoff: float Returns ------- snr (list): List of snr time series. norm (list): List of normalizations factors for the snr time series. """ snrs = [] norms = [] for bank_template in filters: # For every template compute the snr against the stilde segment snr, _, norm = matched_filter_core( bank_template, stilde, h_norm=bank_template.sigmasq(psd), psd=None, low_frequency_cutoff=low_frequency_cutoff) # SNR time series stored here snrs.append(snr) # Template normalization factor stored here norms.append(norm) return snrs, norms
[docs]def template_overlaps(bank_filters, template, psd, low_frequency_cutoff): """ This functions calculates the overlaps between the template and the bank veto templates. Parameters ---------- bank_filters: List of FrequencySeries template: FrequencySeries psd: FrequencySeries low_frequency_cutoff: float Returns ------- overlaps: List of complex overlap values. """ overlaps = [] template_ow = template / psd for bank_template in bank_filters: overlap = overlap_cplx(template_ow, bank_template, low_frequency_cutoff=low_frequency_cutoff, normalized=False) norm = sqrt(1 / template.sigmasq(psd) / bank_template.sigmasq(psd)) overlaps.append(overlap * norm) if (abs(overlaps[-1]) > 0.99): errMsg = "Overlap > 0.99 between bank template and filter. " errMsg += "This bank template will not be used to calculate " errMsg += "bank chisq for this filter template. The expected " errMsg += "value will be added to the chisq to account for " errMsg += "the removal of this template.\n" errMsg += "Masses of filter template: %e %e\n" \ %(template.params.mass1, template.params.mass2) errMsg += "Masses of bank filter template: %e %e\n" \ %(bank_template.params.mass1, bank_template.params.mass2) errMsg += "Overlap: %e" %(abs(overlaps[-1])) return overlaps
[docs]def bank_chisq_from_filters(tmplt_snr, tmplt_norm, bank_snrs, bank_norms, tmplt_bank_matches, indices=None): """ This function calculates and returns a TimeSeries object containing the bank veto calculated over a segment. Parameters ---------- tmplt_snr: TimeSeries The SNR time series from filtering the segment against the current search template tmplt_norm: float The normalization factor for the search template bank_snrs: list of TimeSeries The precomputed list of SNR time series between each of the bank veto templates and the segment bank_norms: list of floats The normalization factors for the list of bank veto templates (usually this will be the same for all bank veto templates) tmplt_bank_matches: list of floats The complex overlap between the search template and each of the bank templates indices: {None, Array}, optional Array of indices into the snr time series. If given, the bank chisq will only be calculated at these values. Returns ------- bank_chisq: TimeSeries of the bank vetos """ if indices is not None: tmplt_snr = Array(tmplt_snr, copy=False) bank_snrs_tmp = [] for bank_snr in bank_snrs: bank_snrs_tmp.append(bank_snr.take(indices)) bank_snrs=bank_snrs_tmp # Initialise bank_chisq as 0s everywhere bank_chisq = zeros(len(tmplt_snr), dtype=real_same_precision_as(tmplt_snr)) # Loop over all the bank templates for i in range(len(bank_snrs)): bank_match = tmplt_bank_matches[i] if (abs(bank_match) > 0.99): # Not much point calculating bank_chisquared if the bank template # is very close to the filter template. Can also hit numerical # error due to approximations made in this calculation. # The value of 2 is the expected addition to the chisq for this # template bank_chisq += 2. continue bank_norm = sqrt((1 - bank_match*bank_match.conj()).real) bank_SNR = bank_snrs[i] * (bank_norms[i] / bank_norm) tmplt_SNR = tmplt_snr * (bank_match.conj() * tmplt_norm / bank_norm) bank_SNR = Array(bank_SNR, copy=False) tmplt_SNR = Array(tmplt_SNR, copy=False) bank_chisq += (bank_SNR - tmplt_SNR).squared_norm() if indices is not None: return bank_chisq else: return TimeSeries(bank_chisq, delta_t=tmplt_snr.delta_t, epoch=tmplt_snr.start_time, copy=False)
[docs]class SingleDetBankVeto(object): """This class reads in a template bank file for a bank veto, handles the memory management of its filters internally, and calculates the bank veto TimeSeries. """ def __init__(self, bank_file, flen, delta_f, f_low, cdtype, approximant=None, **kwds): if bank_file is not None: = True self.column_name = "bank_chisq" self.table_dof_name = "bank_chisq_dof" self.cdtype = cdtype self.delta_f = delta_f self.f_low = f_low self.seg_len_freq = flen self.seg_len_time = (self.seg_len_freq-1)*2"Read in bank veto template bank") bank_veto_bank = FilterBank(bank_file, self.seg_len_freq, self.delta_f, self.cdtype, low_frequency_cutoff=f_low, approximant=approximant, **kwds) self.filters = list(bank_veto_bank) self.dof = len(bank_veto_bank) * 2 self._overlaps_cache = {} self._segment_snrs_cache = {} else: = False
[docs] def cache_segment_snrs(self, stilde, psd): key = (id(stilde), id(psd)) if key not in self._segment_snrs_cache:"Precalculate the bank veto template snrs") data = segment_snrs(self.filters, stilde, psd, self.f_low) self._segment_snrs_cache[key] = data return self._segment_snrs_cache[key]
[docs] def cache_overlaps(self, template, psd): key = (id(template.params), id(psd)) if key not in self._overlaps_cache:"...Calculate bank veto overlaps") o = template_overlaps(self.filters, template, psd, self.f_low) self._overlaps_cache[key] = o return self._overlaps_cache[key]
[docs] def values(self, template, psd, stilde, snrv, norm, indices): """ Returns ------- bank_chisq_from_filters: TimeSeries of bank veto values - if indices is None then evaluated at all time samples, if not then only at requested sample indices bank_chisq_dof: int, approx number of statistical degrees of freedom """ if"...Doing bank veto") overlaps = self.cache_overlaps(template, psd) bank_veto_snrs, bank_veto_norms = self.cache_segment_snrs(stilde, psd) chisq = bank_chisq_from_filters(snrv, norm, bank_veto_snrs, bank_veto_norms, overlaps, indices) dof = numpy.repeat(self.dof, len(chisq)) return chisq, dof else: return None, None
[docs]class SingleDetSkyMaxBankVeto(SingleDetBankVeto): """Stub for precessing bank veto if anyone ever wants to code it up. """ def __init__(self, *args, **kwds): super(SingleDetSkyMaxBankVeto, self).__init__(*args, **kwds)
[docs] def values(self, *args, **kwargs): if err_msg = "Precessing single detector sky-max bank veto has not " err_msg += "been written. If you want to use it, why not help " err_msg += "write it?" raise NotImplementedError(err_msg) else: return None, None