Mercurial > repos > earlhaminst > ensembl_longest_cds_per_gene
view ensembl_longest_cds_per_gene.py @ 0:4dba69135845 draft
planemo upload for repository https://github.com/TGAC/earlham-galaxytools/tree/master/tools/ensembl_longest_cds_per_gene commit 26c70aecb56c19099455bb5a432615b09ad322d1
author | earlhaminst |
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date | Tue, 07 Mar 2017 05:54:30 -0500 |
parents | |
children | 6cf9f7f6509c |
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""" This script reads a CDS FASTA file from Ensembl and outputs a FASTA file with only the longest CDS sequence for each gene. The header of the sequences in the output file will be the transcript id without version. """ from __future__ import print_function import collections import optparse import sys Sequence = collections.namedtuple('Sequence', ['header', 'sequence']) def FASTAReader_gen(fasta_filename): with open(fasta_filename) as fasta_file: line = fasta_file.readline() while True: if not line: return assert line.startswith('>'), "FASTA headers must start with >" header = line.rstrip() sequence_parts = [] line = fasta_file.readline() while line and line[0] != '>': sequence_parts.append(line.rstrip()) line = fasta_file.readline() sequence = "\n".join(sequence_parts) yield Sequence(header, sequence) def remove_id_version(s): """ Remove the optional '.VERSION' from an Ensembl id. """ return s.split('.')[0] parser = optparse.OptionParser() parser.add_option('-f', '--fasta', dest="input_fasta_filename", help='CDS file in FASTA format from Ensembl') parser.add_option('-o', '--output', dest="output_fasta_filename", help='Output FASTA file name') options, args = parser.parse_args() if options.input_fasta_filename is None: raise Exception('-f option must be specified') if options.output_fasta_filename is None: raise Exception('-o option must be specified') gene_transcripts_dict = dict() for entry in FASTAReader_gen(options.input_fasta_filename): transcript_id, rest = entry.header[1:].split(' ', 1) transcript_id = remove_id_version(transcript_id) gene_id = None for s in rest.split(' '): if s.startswith('gene:'): gene_id = remove_id_version(s[5:]) break else: print("Gene id not found in header '%s'" % entry.header, file=sys.stderr) continue if gene_id in gene_transcripts_dict: gene_transcripts_dict[gene_id].append((transcript_id, len(entry.sequence))) else: gene_transcripts_dict[gene_id] = [(transcript_id, len(entry.sequence))] # For each gene, select the transcript with the longest sequence # If more than one transcripts have the same longest sequence for a gene, the # first one to appear in the FASTA file is selected selected_transcript_ids = [max(transcript_id_lengths, key=lambda _: _[1])[0] for transcript_id_lengths in gene_transcripts_dict.values()] with open(options.output_fasta_filename, 'w') as output_fasta_file: for entry in FASTAReader_gen(options.input_fasta_filename): transcript_id = remove_id_version(entry.header[1:].split(' ')[0]) if transcript_id in selected_transcript_ids: output_fasta_file.write(">%s\n%s\n" % (transcript_id, entry.sequence))