Mercurial > repos > ulfschaefer > filter_vcf
view phe/variant_filters/MQ0Filter.py @ 11:cd59be4a7fe3 draft default tip
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author | ulfschaefer |
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date | Mon, 21 Dec 2015 11:12:19 -0500 |
parents | c2f8e7580133 |
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'''Filter VCF on MQ filter. Created on 24 Sep 2015 @author: alex ''' import argparse import logging from phe.variant_filters import PHEFilterBase class MQ0Filter(PHEFilterBase): '''Filter sites by MQ0 (Total Mapping Quality Zero Reads) to DP ratio.''' name = "MinMQ0" _default_threshold = 0.05 parameter = "mq0_ratio" @classmethod def customize_parser(self, parser): arg_name = self.parameter.replace("_", "-") parser.add_argument("--%s" % arg_name, type=float, default=self._default_threshold, help="Filter sites below given MQ score (default: %s)" % self._default_threshold) def __init__(self, args): """Min Mapping Quality Zero constructor.""" # This needs to happen first, because threshold is initialised here. super(MQ0Filter, self).__init__(args) # Change the threshold to custom gq value. self.threshold = self._default_threshold if isinstance(args, argparse.Namespace): self.threshold = args.mq_score elif isinstance(args, dict): try: self.threshold = float(args.get(self.parameter)) except (TypeError, ValueError): logging.error("Could not retrieve threshold from %s", args.get(self.parameter)) logging.error("This parameter requires to be a float!") raise Exception("Could not create MQ0 filter from parameters: %s" % args) def __call__(self, record): """Filter a :py:class:`vcf.model._Record`.""" good_record = self._check_record(record) if good_record is not True: return good_record record_mq = record.INFO.get("MQ0") if record_mq: # We consider DO from INFO not samples because MQ0 is also from INFO. record_mq /= float(record.INFO.get("DP")) if record_mq is None or record_mq > self.threshold: # FIXME: when record_mq is None, i,e, error/missing, what do you do? return record_mq or False else: return None def short_desc(self): short_desc = self.__doc__ or '' if short_desc: short_desc = "%s (MQ0 > %s)" % (short_desc, self.threshold) return short_desc