Mercurial > repos > peterjc > get_orfs_or_cdss
view tools/get_orfs_or_cdss/get_orfs_or_cdss.py @ 7:705a2e2df7fb draft
v0.1.1 fix typo; v0.1.0 BED output (Eric Rasche), NCBI genetic code 24; v0.0.7 embeds citation
author | peterjc |
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date | Thu, 30 Jul 2015 12:35:31 -0400 |
parents | 5208c15805ec |
children | 09a8be9247ca |
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#!/usr/bin/env python """Find ORFs in a nucleotide sequence file. For more details, see the help text and argument descriptions in the accompanying get_orfs_or_cdss.xml file which defines a Galaxy interface. This tool is a short Python script which requires Biopython. If you use this tool in scientific work leading to a publication, please cite the Biopython application note: Cock et al 2009. Biopython: freely available Python tools for computational molecular biology and bioinformatics. Bioinformatics 25(11) 1422-3. http://dx.doi.org/10.1093/bioinformatics/btp163 pmid:19304878. This script is copyright 2011-2013 by Peter Cock, The James Hutton Institute (formerly SCRI), Dundee, UK. All rights reserved. See accompanying text file for licence details (MIT licence). This is version 0.1.0 of the script. """ import sys import re from optparse import OptionParser def sys_exit(msg, err=1): sys.stderr.write(msg.rstrip() + "\n") sys.exit(err) usage = """Use as follows: $ python get_orfs_or_cdss.py -i genome.fa -f fasta --table 11 -t CDS -e open -m all -s both --on cds.nuc.fa --op cds.protein.fa --ob cds.bed """ try: from Bio.Seq import Seq, reverse_complement, translate from Bio.SeqRecord import SeqRecord from Bio import SeqIO from Bio.Data import CodonTable except ImportError: sys_exit("Missing Biopython library") parser = OptionParser(usage=usage) parser.add_option('-i', '--input', dest='input_file', default=None, help='Input fasta file', metavar='FILE') parser.add_option('-f', '--format', dest='seq_format', default='fasta', help='Sequence format (e.g. fasta, fastq, sff)') parser.add_option('--table', dest='table', default=1, help='NCBI Translation table', type='int') parser.add_option('-t', '--ftype', dest='ftype', type='choice', choices=['CDS', 'ORF'], default='ORF', help='Find ORF or CDSs') parser.add_option('-e', '--ends', dest='ends', type='choice', choices=['open', 'closed'], default='closed', help='Open or closed. Closed ensures start/stop codons are present') parser.add_option('-m', '--mode', dest='mode', type='choice', choices=['all', 'top', 'one'], default='all', help='Output all ORFs/CDSs from sequence, all ORFs/CDSs ' 'with max length, or first with maximum length') parser.add_option('--min_len', dest='min_len', default=10, help='Minimum ORF/CDS length', type='int') parser.add_option('-s', '--strand', dest='strand', type='choice', choices=['forward', 'reverse', 'both'], default='both', help='Strand to search for features on') parser.add_option('--on', dest='out_nuc_file', default=None, help='Output nucleotide sequences, or - for STDOUT', metavar='FILE') parser.add_option('--op', dest='out_prot_file', default=None, help='Output protein sequences, or - for STDOUT', metavar='FILE') parser.add_option('--ob', dest='out_bed_file', default=None, help='Output BED file, or - for STDOUT', metavar='FILE') parser.add_option('-v', '--version', dest='version', default=False, action='store_true', help='Show version and quit') options, args = parser.parse_args() if options.version: print "v0.1.0" sys.exit(0) try: table_obj = CodonTable.ambiguous_generic_by_id[options.table] except KeyError: sys_exit("Unknown codon table %i" % options.table) if options.seq_format.lower()=="sff": seq_format = "sff-trim" elif options.seq_format.lower()=="fasta": seq_format = "fasta" elif options.seq_format.lower().startswith("fastq"): seq_format = "fastq" else: sys_exit("Unsupported file type %r" % options.seq_format) print "Genetic code table %i" % options.table print "Minimum length %i aa" % options.min_len #print "Taking %s ORF(s) from %s strand(s)" % (mode, strand) starts = sorted(table_obj.start_codons) assert "NNN" not in starts re_starts = re.compile("|".join(starts)) stops = sorted(table_obj.stop_codons) assert "NNN" not in stops re_stops = re.compile("|".join(stops)) def start_chop_and_trans(s, strict=True): """Returns offset, trimmed nuc, protein.""" if strict: assert s[-3:] in stops, s assert len(s) % 3 == 0 for match in re_starts.finditer(s): #Must check the start is in frame start = match.start() if start % 3 == 0: n = s[start:] assert len(n) % 3 == 0, "%s is len %i" % (n, len(n)) if strict: t = translate(n, options.table, cds=True) else: #Use when missing stop codon, t = "M" + translate(n[3:], options.table, to_stop=True) return start, n, t return None, None, None def break_up_frame(s): """Returns offset, nuc, protein.""" start = 0 for match in re_stops.finditer(s): index = match.start() + 3 if index % 3 != 0: continue n = s[start:index] if options.ftype=="CDS": offset, n, t = start_chop_and_trans(n) else: offset = 0 t = translate(n, options.table, to_stop=True) if n and len(t) >= options.min_len: yield start + offset, n, t start = index if options.ends == "open": #No stop codon, Biopython's strict CDS translate will fail n = s[start:] #Ensure we have whole codons #TODO - Try appending N instead? #TODO - Do the next four lines more elegantly if len(n) % 3: n = n[:-1] if len(n) % 3: n = n[:-1] if options.ftype=="CDS": offset, n, t = start_chop_and_trans(n, strict=False) else: offset = 0 t = translate(n, options.table, to_stop=True) if n and len(t) >= options.min_len: yield start + offset, n, t def get_all_peptides(nuc_seq): """Returns start, end, strand, nucleotides, protein. Co-ordinates are Python style zero-based. """ #TODO - Refactor to use a generator function (in start order) #rather than making a list and sorting? answer = [] full_len = len(nuc_seq) if options.strand != "reverse": for frame in range(0,3): for offset, n, t in break_up_frame(nuc_seq[frame:]): start = frame + offset #zero based answer.append((start, start + len(n), +1, n, t)) if options.strand != "forward": rc = reverse_complement(nuc_seq) for frame in range(0,3) : for offset, n, t in break_up_frame(rc[frame:]): start = full_len - frame - offset #zero based answer.append((start - len(n), start, -1, n ,t)) answer.sort() return answer def get_top_peptides(nuc_seq): """Returns all peptides of max length.""" values = list(get_all_peptides(nuc_seq)) if not values: raise StopIteration max_len = max(len(x[-1]) for x in values) for x in values: if len(x[-1]) == max_len: yield x def get_one_peptide(nuc_seq): """Returns first (left most) peptide with max length.""" values = list(get_top_peptides(nuc_seq)) if not values: raise StopIteration yield values[0] if options.mode == "all": get_peptides = get_all_peptides elif options.mode == "top": get_peptides = get_top_peptides elif options.mode == "one": get_peptides = get_one_peptide in_count = 0 out_count = 0 if options.out_nuc_file == "-": out_nuc = sys.stdout else: out_nuc = open(options.out_nuc_file, "w") if options.out_prot_file == "-": out_prot = sys.stdout else: out_prot = open(options.out_prot_file, "w") if options.out_bed_file == "-": out_bed = sys.stdout else: out_bed = open(options.out_bed_file, "w") for record in SeqIO.parse(options.input_file, seq_format): for i, (f_start, f_end, f_strand, n, t) in enumerate(get_peptides(str(record.seq).upper())): out_count += 1 if f_strand == +1: loc = "%i..%i" % (f_start+1, f_end) else: loc = "complement(%i..%i)" % (f_start+1, f_end) descr = "length %i aa, %i bp, from %s of %s" \ % (len(t), len(n), loc, record.description) fid = record.id + "|%s%i" % (options.ftype, i+1) r = SeqRecord(Seq(n), id = fid, name = "", description= descr) t = SeqRecord(Seq(t), id = fid, name = "", description= descr) SeqIO.write(r, out_nuc, "fasta") SeqIO.write(t, out_prot, "fasta") out_bed.write('\t'.join(map(str,[record.id, f_start, f_end, fid, 0, '+' if f_strand == +1 else '-'])) + '\n') in_count += 1 if out_nuc is not sys.stdout: out_nuc.close() if out_prot is not sys.stdout: out_prot.close() if out_bed is not sys.stdout: out_bed.close() print "Found %i %ss in %i sequences" % (out_count, options.ftype, in_count)