rate_posterior: add --ranking-stat-threshold

- allow the threshold to be adjusted manually (default is the current
  behaviour, which is to set the threshold from the lower bound of the
  extinction model's domain of validity)

gstlal-inspiral/bin/gstlal_inspiral_rate_posterior

@@ -97,6 +97,7 @@ def parse_command_line():
 	parser.add_option("--chain-file", metavar = "filename", help = "Read chain from this file, save chain to this file.")
 	parser.add_option("--ranking-stat-pdf", metavar = "filename", action = "append", help = "Load ranking statistic PDFs for the signal and noise models from this file.  Can be given multiple times.")
 	parser.add_option("--ranking-stat-pdf-cache", metavar = "filename", help = "Load ranking statistic PDFs for the signal and noise models from the files in this LAL cache.")
+	parser.add_option("--ranking-stat-threshold", metavar = "value", type = "float", help = "Only consider candidates at or above this value of the ranking statistic.  The default is to set the threshold automatically from the extinction model's domain of validity.")
 	parser.add_option("-t", "--tmp-space", metavar = "path", help = "Path to a directory suitable for use as a work area while manipulating the database file.  The database file will be worked on in this directory, and then moved to the final location when complete.  This option is intended to improve performance when running in a networked environment, where there might be a local disk with higher bandwidth than is available to the filesystem on which the final output will reside.")
 	parser.add_option("--with-background", action = "store_true", help = "Show background posterior on plot.")
 	parser.add_option("--samples", metavar = "count", type = "int", help = "Run this many samples.  Set to 0 to load and plot the contents of a previously-recorded chain file without doing any additional samples.")
@@ -132,20 +133,21 @@ def parse_command_line():
 #
 
 
-def load_ranking_data(filenames, verbose = False):
+def load_ranking_data(filenames, ln_likelihood_ratio_threshold, verbose = False):
 	if not filenames:
 		raise ValueError("no likelihood files!")
 	rankingstatpdf = far.marginalize_pdf_urls(filenames, "RankingStatPDF", verbose = verbose)
 
-	# determine the treshold below which the extinction model will be
-	# invalid.  FIXME:  this shouldn't have to be repeated in code like
-	# this, the extinction model itself should provide this information
-	# somehow.
-	zl = rankingstatpdf.zero_lag_lr_lnpdf.copy()
-	zl.array[:40] = 0.
-	if not zl.array.any():
-		raise ValueError("zero-lag counts are all zero")
-	ln_likelihood_ratio_threshold, = zl.argmax()
+	if ln_likelihood_ratio_threshold is None:
+		# determine the treshold below which the extinction model
+		# will be invalid.  FIXME:  this shouldn't have to be
+		# repeated in code like this, the extinction model itself
+		# should provide this information somehow.
+		zl = rankingstatpdf.zero_lag_lr_lnpdf.copy()
+		zl.array[:40] = 0.
+		if not zl.array.any():
+			raise ValueError("zero-lag counts are all zero")
+		ln_likelihood_ratio_threshold, = zl.argmax()
 
 	# apply the extinction model
 	rankingstatpdf = rankingstatpdf.new_with_extinction()
@@ -260,7 +262,7 @@ options, paramdict, filenames = parse_command_line()
 
 
 if options.ranking_stat_pdf:
-	rankingstatpdf, ln_likelihood_ratio_threshold = load_ranking_data(options.ranking_stat_pdf, verbose = options.verbose)
+	rankingstatpdf, ln_likelihood_ratio_threshold = load_ranking_data(options.ranking_stat_pdf, options.ln_likelihood_ratio_threshold, verbose = options.verbose)
 else:
 	rankingstatpdf, ln_likelihood_ratio_threshold = None, None