def main():
    parser = argparse.ArgumentParser(
        description=
        'Checks for genes with multiple mRNA children and creates new genes for each.'
    )

    ## output file to be written
    parser.add_argument('-i',
                        '--input_file',
                        type=str,
                        required=True,
                        help='Path to the input GFF3')
    parser.add_argument('-o',
                        '--output_file',
                        type=str,
                        required=False,
                        help='Path to an output file to be created')
    args = parser.parse_args()

    (assemblies, features) = biocodegff.get_gff3_features(args.input_file)

    ## output will either be a file or STDOUT
    ofh = sys.stdout
    if args.output_file is not None:
        ofh = open(args.output_file, 'wt')

    ofh.write("##gff-version 3\n")

    for assembly_id in assemblies:
        current_assembly = assemblies[assembly_id]

        for gene in assemblies[assembly_id].genes():
            rnas_found = 0
            mRNAs = gene.mRNAs()

            for mRNA in mRNAs:
                mRNA_loc = mRNA.location_on(current_assembly)
                rnas_found += 1

                if rnas_found > 1:
                    gene.remove_mRNA(mRNA)

                    print("INFO: splitting mRNA off gene {0}".format(gene.id))
                    new_gene = biothings.Gene(
                        id="{0}_{1}".format(gene.id, rnas_found))
                    new_gene.locate_on(target=current_assembly,
                                       fmin=mRNA_loc.fmin,
                                       fmax=mRNA_loc.fmax,
                                       strand=mRNA_loc.strand)
                    new_gene.add_RNA(mRNA)
                    new_gene.print_as(fh=ofh, format='gff3')

            if len(mRNAs) > 1:
                gene_loc = gene.location_on(current_assembly)
                mRNA_loc = mRNAs[0].location_on(current_assembly)
                gene_loc.fmin = mRNA_loc.fmin
                gene_loc.fmax = mRNA_loc.fmax
                gene_loc.strand = mRNA_loc.strand

            gene.print_as(fh=ofh, format='gff3')
Exemplo n.º 2
0
def print_tbl_from_assemblies(assemblies=None,
                              ofh=None,
                              go_obo=None,
                              lab_name=None):
    """
    Utility function to write a complete NCBI tbl file from a list() of biothings.Assembly objects

    The go_obo option is required if you want to be able to export GO terms in the annotation.  This
    is because, at the time of this writing, there is no standard in GFF for specifying terms as part of
    the 'process', 'function' or 'component' namespaces but the TBL format requires this distinction
    for each term.  This function indexes it instead so this distinction can be made.
    """
    if type(ofh).__name__ != 'TextIOWrapper':
        ofh = sys.stdout  #TextIOWrapper

    if go_obo is None:
        go_idx = None
    else:
        go_idx = go_namespace_index(go_obo)

    for assembly_id in assemblies:
        current_assembly = assemblies[assembly_id]

        ofh.write(">Feature {0}\n".format(assembly_id))

        for gene in sorted(assemblies[assembly_id].genes()):
            rnas_found = 0
            mRNAs = gene.mRNAs()

            for mRNA in mRNAs:
                mRNA_loc = mRNA.location_on(current_assembly)
                rnas_found += 1

                if rnas_found > 1:
                    gene.remove_mRNA(mRNA)

                    print("INFO: splitting mRNA off gene {0}".format(gene.id))
                    new_gene = biothings.Gene(
                        id="{0}_{1}".format(gene.id, rnas_found))
                    new_gene.locate_on(target=current_assembly,
                                       fmin=mRNA_loc.fmin,
                                       fmax=mRNA_loc.fmax,
                                       strand=mRNA_loc.strand)
                    new_gene.add_RNA(mRNA)
                    print_biogene(gene=new_gene,
                                  fh=ofh,
                                  obo_dict=go_idx,
                                  lab_name=lab_name)

            if len(mRNAs) > 1:
                gene_loc = gene.location_on(current_assembly)
                mRNA_loc = mRNAs[0].location_on(current_assembly)
                gene_loc.fmin = mRNA_loc.fmin
                gene_loc.fmax = mRNA_loc.fmax
                gene_loc.strand = mRNA_loc.strand

            print_biogene(gene=gene,
                          fh=ofh,
                          obo_dict=go_idx,
                          lab_name=lab_name)
def parse_gff3(gff3_file):

    assemblies = dict()
    genes = dict()

    for line in open(gff3_file):
        cols = line.split("\t")

        if len(cols) != 9:
            continue

        mol_id = cols[0]

        ## initialize this assembly if we haven't seen it yet
        if mol_id not in assemblies:
            assemblies[mol_id] = biothings.Assembly(id=mol_id)

        current_assembly = assemblies[mol_id]
        rfmin = int(cols[3]) - 1
        rfmax = int(cols[4])
        rstrand = None
        feat_id = column_9_value(cols[8], 'ID')
        #print("Processing feature: ({0})".format(feat_id))

        if cols[6] == '-':
            strand = -1
        elif cols[6] == '+':
            strand = 1
        else:
            strand = 0

        if cols[2] == 'gene':
            gene = biothings.Gene(id=feat_id)
            gene.locate_on(assembly=current_assembly,
                           fmin=rfmin,
                           fmax=rfmax,
                           strand=rstrand)
            genes[feat_id] = gene

        elif cols[2] == 'mRNA':
            mRNA = biothings.mRNA(id=feat_id)
            mRNA.locate_on(assembly=current_assembly,
                           fmin=rfmin,
                           fmax=rfmax,
                           strand=rstrand)
            parent_id = column_9_value(cols[8], 'Parent')
            genes[parent_id].add_mRNA(mRNA)

    return (assemblies, genes)
Exemplo n.º 4
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def main():
    parser = argparse.ArgumentParser(
        description='Splits all GFF3 mRNA isoforms into their own gene models')

    ## Get the variables
    parser.add_argument('-i',
                        '--input_file',
                        type=str,
                        required=True,
                        help='Input GFF3 file')
    parser.add_argument('-o',
                        '--output_file',
                        type=str,
                        required=True,
                        help='Output GFF3 file')
    args = parser.parse_args()
    ofh = open(args.output_file, 'wt')

    print("INFO: Parsing GFF3 features\n")
    (assemblies, ref_features) = biocodegff.get_gff3_features(args.input_file)

    print("INFO: Finding genes with isoforms and splitting them\n")
    ofh.write("##gff-version 3\n")
    for assembly_id in assemblies:
        for gene in assemblies[assembly_id].genes():
            # only changing the gene features with isoforms
            if len(gene.mRNAs()) > 1:
                counter = 1
                for mRNA in gene.mRNAs():
                    new_gene_id = str(gene.id) + "_" + str(counter)
                    counter += 1
                    mRNA_loc = mRNA.location()
                    print("Splitting " + gene.id)
                    # create a new gene model, correcting the gene coords to the mRNA coords
                    new_gene = biothings.Gene(id=new_gene_id)
                    new_gene.locate_on(target=assemblies[assembly_id],
                                       fmin=mRNA_loc.fmin,
                                       fmax=mRNA_loc.fmax,
                                       strand=mRNA_loc.strand)
                    mRNA.parent.id = new_gene_id
                    #Now add the mRNA to the gene model
                    new_gene.add_mRNA(mRNA)
                    # print out the new gene model
                    new_gene.print_as(fh=ofh, source='IGS', format='gff3')
            else:
                gene.print_as(fh=ofh, source='IGS', format='gff3')
Exemplo n.º 5
0
def print_gff3_from_assemblies(assemblies=None, ofh=None):
    """
    Utility function to write a complete GFF3 file from a list() of biothings.Assembly objects
    """
    if type(ofh).__name__ != 'TextIOWrapper':
        ofh = sys.stdout  #TextIOWrapper

    ofh.write("##gff-version 3\n")

    for assembly_id in assemblies:
        current_assembly = assemblies[assembly_id]

        for gene in assemblies[assembly_id].genes():
            rnas_found = 0
            mRNAs = gene.mRNAs()

            for mRNA in mRNAs:
                mRNA_loc = mRNA.location_on(current_assembly)
                rnas_found += 1

                if rnas_found > 1:
                    gene.remove_mRNA(mRNA)

                    print("INFO: splitting mRNA off gene {0}".format(gene.id))
                    new_gene = biothings.Gene(
                        id="{0}_{1}".format(gene.id, rnas_found))
                    new_gene.locate_on(target=current_assembly,
                                       fmin=mRNA_loc.fmin,
                                       fmax=mRNA_loc.fmax,
                                       strand=mRNA_loc.strand)
                    new_gene.add_RNA(mRNA)
                    new_gene.print_as(fh=ofh, format='gff3')

            if len(mRNAs) > 1:
                gene_loc = gene.location_on(current_assembly)
                mRNA_loc = mRNAs[0].location_on(current_assembly)
                gene_loc.fmin = mRNA_loc.fmin
                gene_loc.fmax = mRNA_loc.fmax
                gene_loc.strand = mRNA_loc.strand

            gene.print_as(fh=ofh, format='gff3')
Exemplo n.º 6
0
def main():
    parser = argparse.ArgumentParser( description='Convert PASA GFF file to canonical gene models')

    ## output file to be written
    parser.add_argument('-i', '--input', type=str, required=True, help='Path to a GFF file created by PASA' )
    parser.add_argument('-o', '--output', type=str, required=True, help='Path to an output file to be created' )
    parser.add_argument('-s', '--source', type=str, required=False, default='PASA', help='Value to use for the 2nd (source) column' )
    args = parser.parse_args()

    assemblies = dict()
    current_assembly = None
    
    gene = None
    mRNA = None
    gene_fmin = None
    gene_fmax = None
    gene_strand = None

    ## Used for tracking the exon count for each gene (for ID purposes)
    exon_count_by_mRNA = dict()
    
    fout = open(args.output, mode='wt', encoding='utf-8')
    fout.write("##gff-version 3\n")

    for line in open(args.input):
        cols = line.split("\t")

        if len(cols) != 9:
            continue

        mol_id = cols[0]
        feat_type = cols[2]
        feat_id = biocodegff.column_9_value(cols[8], 'ID')

        # we expect all columns to be cDNA_match
        if feat_type != 'cDNA_match':
            raise Exception("ERROR: expected all columns to be of type 'cDNA_match' but found a {0}".format(feat_type))

        ## initialize this assembly if we haven't seen it yet
        if mol_id not in assemblies:
            assemblies[mol_id] = biothings.Assembly( id=mol_id )

        if gene is None or feat_id != gene.id:
            if gene is not None:
                # finish the previous one first
                mRNA.locate_on( target=current_assembly, fmin=gene_fmin, fmax=gene_fmax, strand=gene_strand )
                gene.locate_on( target=current_assembly, fmin=gene_fmin, fmax=gene_fmax, strand=gene_strand )
                gene.add_mRNA(mRNA)
                current_assembly.add_gene( gene )
                gene.print_as(fh=fout, source=args.source, format='gff3')

            # now start a new one
            gene = biothings.Gene( id=feat_id )
            mRNA = biothings.mRNA( id="{0}.mRNA".format(feat_id), parent=gene )
            exon_count_by_mRNA[mRNA.id] = 0
            
            gene_fmin = int(cols[3]) - 1
            gene_fmax = int(cols[4])
            gene_strand = cols[6]

        current_assembly = assemblies[mol_id]
            
        # each row is a new CDS/exon for the current mRNA
        CDS = biothings.CDS( id="{0}.CDS".format(feat_id), parent=mRNA.id )
        # FIX THIS PHASE
        CDS.locate_on( target=current_assembly, fmin=int(cols[3]) - 1, fmax=int(cols[4]), strand=cols[6], phase='.' )
        mRNA.add_CDS(CDS)
        
        exon_count_by_mRNA[mRNA.id] += 1
        exon_id = "{0}.exon{1}".format(mRNA.id, exon_count_by_mRNA[mRNA.id])
        exon = biothings.Exon( id=exon_id, parent=mRNA.id )
        exon.locate_on( target=current_assembly, fmin=int(cols[3]) - 1, fmax=int(cols[4]), strand=cols[6] )
        mRNA.add_exon(exon)

        if int(cols[3]) - 1 < gene_fmin:
            gene_fmin = int(cols[3]) - 1

        if int(cols[4]) > gene_fmax:
            gene_fmax = int(cols[4])

    # don't orphan the last one
    if gene is not None:
        # finish the previous one first
        mRNA.locate_on( target=current_assembly, fmin=gene_fmin, fmax=gene_fmax, strand=gene_strand )
        gene.locate_on( target=current_assembly, fmin=gene_fmin, fmax=gene_fmax, strand=gene_strand )
        gene.add_mRNA(mRNA)
        current_assembly.add_gene( gene )
        gene.print_as(fh=fout, source=args.source, format='gff3')
def main():
    parser = argparse.ArgumentParser(
        description='Converts CEGMA GFF output to spec-legal GFF3')

    # output file to be written
    parser.add_argument('-i',
                        '--input_file',
                        type=str,
                        required=True,
                        help='Path to an input file to parse')
    parser.add_argument('-o',
                        '--output_file',
                        type=str,
                        required=True,
                        help='Path to an output file to be created')

    args = parser.parse_args()

    fout = open(args.output_file, 'w')
    fout.write("##gff-version 3\n")

    assemblies = dict()
    current_assembly = None
    current_gene = None
    current_mRNA = None

    current_gene_fmin = None
    current_gene_fmax = None
    current_gene_strand = None

    next_id_nums = {'gene': 1, 'mRNA': 1, 'CDS': 1, 'exon': 1}
    exon_column_types = ['First', 'Internal', 'Terminal', 'Single']

    for line in open(args.input_file, 'r'):
        if line.startswith('#'):
            continue

        cols = line.split("\t")

        if len(cols) != 9:
            continue

        mol_id = cols[0]
        feat_type = cols[2]
        feat_fmin = int(cols[3]) - 1
        feat_fmax = int(cols[4])

        if feat_type == 'Single' or feat_type == 'First':
            # If there's an existing gene already, print it out
            if current_gene is not None:
                current_gene.locate_on(target=current_assembly,
                                       fmin=current_gene_fmin,
                                       fmax=current_gene_fmax,
                                       strand=current_gene_strand)
                current_mRNA.locate_on(target=current_assembly,
                                       fmin=current_gene_fmin,
                                       fmax=current_gene_fmax,
                                       strand=current_gene_strand)

                #current_gene.print_as(format='text')
                current_gene.print_as(fh=fout, source='cegma', format='gff3')

            # initialize this assembly if we haven't seen it yet
            if mol_id not in assemblies:
                assemblies[mol_id] = biothings.Assembly(id=mol_id)

            current_assembly = assemblies[mol_id]

            feat_id = "cegma.gene.{0}".format(next_id_nums['gene'])
            next_id_nums['gene'] += 1
            gene = biothings.Gene(id=feat_id)
            current_gene = gene
            current_gene_strand = cols[6]
            current_gene_fmin = feat_fmin
            current_gene_fmax = feat_fmax

            mRNA_id = "cegma.mRNA.{0}".format(next_id_nums['mRNA'])
            next_id_nums['mRNA'] += 1

            mRNA = biothings.mRNA(id=mRNA_id, parent=gene)
            gene.add_mRNA(mRNA)
            current_mRNA = mRNA

        # CEGMA versions < 2.5 had two rows for each exon.  We don't need to process both of them, so
        #  we skip the Exon one because its phase information is incorrect.
        if feat_type in exon_column_types:
            CDS_id = "cegma.CDS.{0}".format(next_id_nums['CDS'])
            next_id_nums['CDS'] += 1
            CDS = biothings.CDS(id=CDS_id, parent=current_mRNA)
            CDS.locate_on(target=current_assembly,
                          fmin=feat_fmin,
                          fmax=feat_fmax,
                          strand=cols[6],
                          phase=cols[7])
            current_mRNA.add_CDS(CDS)

            exon_id = "cegma.exon.{0}".format(next_id_nums['exon'])
            next_id_nums['exon'] += 1
            exon = biothings.Exon(id=exon_id, parent=current_mRNA)
            exon.locate_on(target=current_assembly,
                           fmin=feat_fmin,
                           fmax=feat_fmax,
                           strand=cols[6])
            mRNA.add_exon(exon)

            if feat_fmin < current_gene_fmin:
                current_gene_fmin = feat_fmin

            if feat_fmax > current_gene_fmax:
                current_gene_fmax = feat_fmax

    # don't forget the last gene
    if current_gene is not None:
        current_gene.locate_on(target=current_assembly,
                               fmin=current_gene_fmin,
                               fmax=current_gene_fmax,
                               strand=current_gene_strand)
        current_mRNA.locate_on(target=current_assembly,
                               fmin=current_gene_fmin,
                               fmax=current_gene_fmax,
                               strand=current_gene_strand)
        current_gene.print_as(fh=fout, source='cegma', format='gff3')
Exemplo n.º 8
0
def get_gff3_features(gff3_file, assemblies=None):
    '''
    Parses the passed GFF3 file and returns two dicts, loaded with biocode.biothings objects:

    1. The first dict are the Assembly objects, keyed on assembly ID.  Each Assembly has all of the
       children populated, so you can fully recover gene, RNA, exon and CDS features iterating on
       the assembly.
    2. The second dist is a flat structure of all the descendent feature objects of the Assemblies
       keyed by the feature IDs.

    See the documentation for each feature type in biocode.biothings for more info
    '''

    if assemblies is None:
        assemblies = dict()

    features = dict()

    # these are related to parsing any embedded FASTA
    in_fasta_section = False
    is_assembly_fasta = False
    current_fasta_id = None

    for line in open(gff3_file):
        #print("INFO: processing line: {0}".format(line))

        if in_fasta_section == True:
            m = re.search('>(\S+)\s*(.*)', line)
            if m:
                current_fasta_id = m.group(1)

                if current_fasta_id in assemblies:
                    is_assembly_fasta = True
                else:
                    is_assembly_fasta = False

            else:
                if is_assembly_fasta == True:
                    # must be a sequence line for an assembly
                    # python 2.6+ makes string concatenation amortized O(n)
                    #  http://stackoverflow.com/a/4435752/1368079
                    assemblies[current_fasta_id].residues += str(line.rstrip())
                    assemblies[current_fasta_id].length = len(
                        assemblies[current_fasta_id].residues)

            continue

        elif line.startswith("##FASTA"):
            # all data to the end of the file must be FASTA
            in_fasta_section = True
            continue

        # ignore all other comments
        if line.startswith('#'):
            continue

        cols = line.split("\t")

        if len(cols) != 9:
            continue

        mol_id = cols[0]

        # initialize this assembly if we haven't seen it yet
        if mol_id not in assemblies:
            assemblies[mol_id] = biothings.Assembly(id=mol_id, residues='')

        current_assembly = assemblies[mol_id]
        rfmin = int(cols[3]) - 1
        rfmax = int(cols[4])
        rstrand = None
        atts = column_9_dict(cols[8])
        feat_id = atts.get('ID')
        parent_id = atts.get('Parent')
        parent_feat = None

        # sanity check
        if rfmin > rfmax:
            raise Exception(
                "ERROR: Coordinates in GFF for feature id {0} appear to be reversed and violate GFF3 specification: {1} > {2}"
                .format(feat_id, cols[3], cols[4]))

        if 'locus_tag' in atts:
            locus_tag = atts['locus_tag']
        else:
            locus_tag = None

        # shared features is not yet supported
        if isinstance(parent_id, list):
            raise Exception(
                "This line contains a shared feature with multiple parents.  This isn't yet supported:\n{0}"
                .format(line))

        if parent_id is not None:
            if parent_id in features:
                parent_feat = features[parent_id]
            else:
                raise Exception(
                    "Error in GFF3: Parent {0} referenced by a child feature before it was defined"
                    .format(parent_id))

        if cols[6] == '-':
            rstrand = -1
        elif cols[6] == '+':
            rstrand = 1
        else:
            rstrand = 0

        if cols[2] == 'gene':
            gene = biothings.Gene(id=feat_id, locus_tag=locus_tag)
            gene.locate_on(target=current_assembly,
                           fmin=rfmin,
                           fmax=rfmax,
                           strand=rstrand)
            features[feat_id] = gene
            current_assembly.add_gene(gene)

        elif cols[2] == 'mRNA':
            mRNA = biothings.mRNA(id=feat_id,
                                  parent=parent_feat,
                                  locus_tag=locus_tag)
            mRNA.locate_on(target=current_assembly,
                           fmin=rfmin,
                           fmax=rfmax,
                           strand=rstrand)
            parent_feat.add_mRNA(mRNA)
            features[feat_id] = mRNA

        elif cols[2] == 'rRNA':
            rRNA = biothings.rRNA(id=feat_id,
                                  parent=parent_feat,
                                  locus_tag=locus_tag)
            rRNA.locate_on(target=current_assembly,
                           fmin=rfmin,
                           fmax=rfmax,
                           strand=rstrand)
            parent_feat.add_rRNA(rRNA)
            features[feat_id] = rRNA

        elif cols[2] == 'tRNA':
            tRNA = biothings.tRNA(id=feat_id,
                                  parent=parent_feat,
                                  locus_tag=locus_tag)
            tRNA.locate_on(target=current_assembly,
                           fmin=rfmin,
                           fmax=rfmax,
                           strand=rstrand)
            parent_feat.add_tRNA(tRNA)
            features[feat_id] = tRNA

        elif cols[2] == 'exon':
            exon = biothings.Exon(id=feat_id, parent=parent_feat)
            exon.locate_on(target=current_assembly,
                           fmin=rfmin,
                           fmax=rfmax,
                           strand=rstrand)
            parent_feat.add_exon(exon)
            features[feat_id] = exon

        elif cols[2] == 'CDS':
            CDS = biothings.CDS(id=feat_id, parent=parent_feat)
            CDS.locate_on(target=current_assembly,
                          fmin=rfmin,
                          fmax=rfmax,
                          strand=rstrand)
            parent_feat.add_CDS(CDS)
            features[feat_id] = CDS

        elif cols[2] == 'polypeptide':
            polypeptide = biothings.Polypeptide(id=feat_id, parent=parent_feat)
            polypeptide.locate_on(target=current_assembly,
                                  fmin=rfmin,
                                  fmax=rfmax,
                                  strand=rstrand)
            parent_feat.add_polypeptide(polypeptide)
            polypeptide.annotation = parse_annotation_from_column_9(cols[8])
            features[feat_id] = polypeptide

        elif cols[2] == 'five_prime_UTR':
            utr = biothings.FivePrimeUTR(id=feat_id, parent=parent_feat)
            utr.locate_on(target=current_assembly,
                          fmin=rfmin,
                          fmax=rfmax,
                          strand=rstrand)
            parent_feat.add_five_prime_UTR(utr)
            features[feat_id] = utr

        elif cols[2] == 'three_prime_UTR':
            utr = biothings.ThreePrimeUTR(id=feat_id, parent=parent_feat)
            utr.locate_on(target=current_assembly,
                          fmin=rfmin,
                          fmax=rfmax,
                          strand=rstrand)
            parent_feat.add_three_prime_UTR(utr)
            features[feat_id] = utr

        else:
            sys.stderr.write("Skipping feature {0} with type {1}\n".format(
                feat_id, cols[2]))
            continue

        features[feat_id].length = rfmax - rfmin

    return (assemblies, features)
def main():
    parser = argparse.ArgumentParser(
        description='Metagenemark GFF -> GFF3 conversion script')

    ## output file to be written
    parser.add_argument('-i',
                        '--input',
                        type=str,
                        required=True,
                        help='Path to a GFF file created by Metagenemark')
    parser.add_argument('-o',
                        '--output',
                        type=str,
                        required=True,
                        help='Path to an output file to be created')
    parser.add_argument('-p',
                        '--prefix',
                        type=str,
                        required=True,
                        help='Prefix to use in ID generation')
    parser.add_argument('-pf',
                        '--protein_fasta',
                        type=str,
                        required=False,
                        help='Optional protein FASTA to be written')
    args = parser.parse_args()

    assemblies = dict()
    current_assembly = None

    # key like 2 = SRS014890.polypeptide.2
    polypeptide_lookup = dict()
    writing_protein = False

    gene = None
    mRNAs = dict()
    current_sequence = None
    current_gene_comment_lines = list()

    fout = open(args.output, mode='wt', encoding='utf-8')
    fout.write("##gff-version 3\n")

    if args.protein_fasta is not None:
        protein_out = open(args.protein_fasta, mode='wt', encoding='utf-8')

    for line in open(args.input):
        if line.startswith("#"):
            if line.startswith("##FASTA"):
                current_gene_comment_lines.append("#{0}".format(line))

            elif line.startswith("##end-Protein"):
                writing_protein = False
                current_gene_comment_lines.append(line)

            # since we're already doing our own header, don't duplicate the old one
            elif line.startswith("##gff-version"):
                continue
            else:
                if line.startswith("##Protein "):
                    m = re.match("##Protein (\d+)", line)
                    if m:
                        writing_protein = True
                        protein_out.write(">{0}\n".format(
                            polypeptide_lookup[m.group(1)]))
                    else:
                        raise Exception(
                            "ERROR: Expected line to match: ##Protein N")
                elif writing_protein == True:
                    protein_out.write(line[2:])

                current_gene_comment_lines.append(line)

        else:
            cols = line.split("\t")

            if len(cols) != 9:
                continue

            mol_id = cols[0]
            mol_id_m = re.match('^(\S+) ', mol_id)

            if mol_id_m:
                print("MATCH!")
                mol_id = mol_id_m.group(1)

            feat_type = cols[2]

            ## we expect only gene types here
            if feat_type not in ['gene', 'CDS']:
                raise Exception(
                    "ERROR: expected only 'gene' or 'CDS' feature types as input (depending on metagenemark version)."
                )

            m_gene = re.match('gene_id[ =](\d+)', cols[8])

            if m_gene:
                gene_num = m_gene.group(1)
            else:
                raise Exception(
                    "ERROR: expected 9th column to have gene ids like: gene_id 5"
                )

            ## initialize this assembly if we haven't seen it yet
            if mol_id not in assemblies:
                assemblies[mol_id] = biothings.Assembly(id=mol_id)

            current_assembly = assemblies[mol_id]

            gene = biothings.Gene(
                id="{0}.gene.{1}".format(args.prefix, gene_num))
            gene.locate_on(target=current_assembly,
                           fmin=int(cols[3]) - 1,
                           fmax=int(cols[4]),
                           strand=cols[6])

            mRNA = biothings.mRNA(id="{0}.mRNA.{1}".format(
                args.prefix, gene_num),
                                  parent=gene.id)
            mRNA.locate_on(target=current_assembly,
                           fmin=int(cols[3]) - 1,
                           fmax=int(cols[4]),
                           strand=cols[6])
            gene.add_mRNA(mRNA)

            CDS = biothings.CDS(id="{0}.CDS.{1}".format(args.prefix, gene_num),
                                parent=mRNA.id)
            CDS.locate_on(target=current_assembly,
                          fmin=int(cols[3]) - 1,
                          fmax=int(cols[4]),
                          strand=cols[6],
                          phase=int(cols[7]))
            mRNA.add_CDS(CDS)

            exon = biothings.Exon(id="{0}.exon.{1}".format(
                args.prefix, gene_num),
                                  parent=mRNA.id)
            exon.locate_on(target=current_assembly,
                           fmin=int(cols[3]) - 1,
                           fmax=int(cols[4]),
                           strand=cols[6])
            mRNA.add_exon(exon)

            polypeptide_id = "{0}.polypeptide.{1}".format(
                args.prefix, gene_num)
            polypeptide = biothings.Polypeptide(id=polypeptide_id,
                                                parent=mRNA.id)
            polypeptide.locate_on(target=current_assembly,
                                  fmin=int(cols[3]) - 1,
                                  fmax=int(cols[4]),
                                  strand=cols[6])
            mRNA.add_polypeptide(polypeptide)
            polypeptide_lookup[gene_num] = polypeptide_id

            gene.print_as(fh=fout, source='GeneMark.hmm', format='gff3')
            fout.write("".join(current_gene_comment_lines))
            current_gene_comment_lines = list()
def main():
    parser = argparse.ArgumentParser( description='A GTF -> GFF3 conversion script for Cufflinks output')

    ## output file to be written
    parser.add_argument('-i', '--input_file', type=str, required=True, help='Path to an input GTF file' )
    parser.add_argument('-o', '--output_file', type=str, required=False, help='Path to an output GFF file to be created' )
    parser.add_argument('-e', '--export_mode', type=str, required=False, default='model', help='Export mode for results (model or cDNA_match)' )
    args = parser.parse_args()

    if args.export_mode not in ['model', 'cDNA_match']:
        raise Exception("ERROR: the only valid values for --export_mode are 'model' or 'cDNA_match'")
    
    ## output will either be a file or STDOUT
    ofh = sys.stdout
    if args.output_file is not None:
        ofh = open(args.output_file, 'wt')

    ofh.write("##gff-version 3\n")

    assemblies = dict()
    current_assembly = None
    current_gene = None
    current_RNA = None
    
    current_match = None

    rna_count_by_gene = defaultdict(int)
    exon_count_by_RNA = defaultdict(int)

    # each gb_record is a SeqRecord object
    for line in open(args.input_file, "r"):
        cols = line.split("\t")

        if len(cols) != 9:
            print("SKIPPING: {0}".format(line))
            continue
        
        mol_id = cols[0]

        if mol_id not in assemblies:
            assemblies[mol_id] = biothings.Assembly( id=mol_id )

        current_assembly = assemblies[mol_id]
        ftype  = cols[2]
        fmin = int(cols[3]) - 1
        fmax = int(cols[4])
        strand = cols[6]
        col9 = cols[8]

        # this makes it look like GFF column 9 so I can use biocodeutils.column_9_value(str, key)
        col9 = col9.replace(' "', '="')
        gene_id       = biocodegff.column_9_value(col9, 'gene_id').replace('"', '')
        transcript_id = biocodegff.column_9_value(col9, 'transcript_id').replace('"', '')
        
        if ftype == 'transcript':
            if args.export_mode == 'model':
                if current_gene is not None and current_gene.id != gene_id:
                    gene.print_as(fh=ofh, source='Cufflinks', format='gff3')

                if current_gene is None or current_gene.id != gene_id:
                    gene = biothings.Gene( id=gene_id )
                    gene.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                    current_gene = gene

                mRNA = biothings.mRNA( id=transcript_id, parent=current_gene )
                mRNA.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                gene.add_mRNA(mRNA)
                current_RNA = mRNA
                exon_count_by_RNA[transcript_id] = 0
                current_CDS_phase = 0

            elif args.export_mode == 'cDNA_match':
                if current_match is not None and current_match.id != transcript_id:
                    match.print_as( fh=ofh, source='Cufflinks', format='gff3' )
                
                match = biothings.Match( id=transcript_id, subclass='cDNA_match', length=fmax - fmin )
                match.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                current_match = match
            
        elif ftype == 'exon':
            exon_number = biocodegff.column_9_value(col9, 'exon_number').replace('"', '')
            
            if args.export_mode == 'model':
                exon_count_by_RNA[transcript_id] += 1

                cds_id = "{0}.CDS.{1}".format( current_RNA.id, exon_count_by_RNA[current_RNA.id] )
                CDS = biothings.CDS( id=cds_id, parent=current_RNA )
                CDS.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand, phase=current_CDS_phase )
                current_RNA.add_CDS(CDS)

                 # calculate the starting phase for the next CDS feature (in case there is one)
                current_CDS_phase = 3 - (((fmax - fmin) - current_CDS_phase) % 3)
                if current_CDS_phase == 3:
                    current_CDS_phase = 0

                exon_id = "{0}.exon.{1}".format( current_RNA.id, exon_count_by_RNA[current_RNA.id] )
                exon = biothings.Exon( id=exon_id, parent=current_RNA )
                exon.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                current_RNA.add_exon(exon)
                
            elif args.export_mode == 'cDNA_match':
                mp_id = "{0}.match_part.{1}".format(transcript_id, exon_number)
                mp = biothings.MatchPart( id=mp_id, parent=current_match, length=fmax - fmin )
                mp.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                current_match.add_part(mp)

    # don't forget to do the last gene, if there were any
    if args.export_mode == 'model':
        if current_gene is not None:
            gene.print_as(fh=ofh, source='GenBank', format='gff3')
            
    elif args.export_mode == 'cDNA_match':
        if current_match is not None:
            match.print_as( fh=ofh, source='Cufflinks', format='gff3' )
Exemplo n.º 11
0
def main():
    parser = argparse.ArgumentParser( description='Convert GenBank flat files to GFF3 format')

    ## output file to be written
    parser.add_argument('-i', '--input_file', type=str, required=True, help='Path to an input GBK file' )
    parser.add_argument('-o', '--output_file', type=str, required=False, help='Path to an output GFF file to be created' )
    parser.add_argument('--with_fasta', dest='fasta', action='store_true', help='Include the FASTA section with genomic sequence at end of file.  (default)' )
    parser.add_argument('--no_fasta', dest='fasta', action='store_false' )
    parser.set_defaults(fasta=True)
    args = parser.parse_args()

    ## output will either be a file or STDOUT
    ofh = sys.stdout
    if args.output_file is not None:
        ofh = open(args.output_file, 'wt')

    ofh.write("##gff-version 3\n")

    assemblies = dict()
    current_assembly = None
    current_gene = None
    current_RNA = None

    rna_count_by_gene = defaultdict(int)
    exon_count_by_RNA = defaultdict(int)

    seqs_pending_writes = False

    features_skipped_count = 0

    # each gb_record is a SeqRecord object
    for gb_record in SeqIO.parse(open(args.input_file, "r"), "genbank"):
        mol_id = gb_record.name

        if mol_id not in assemblies:
            assemblies[mol_id] = biothings.Assembly( id=mol_id )

        if len(str(gb_record.seq)) > 0:
            seqs_pending_writes = True
            assemblies[mol_id].residues = str(gb_record.seq)
            assemblies[mol_id].length = len(str(gb_record.seq))

        current_assembly = assemblies[mol_id]
            
        # each feat is a SeqFeature object
        for feat in gb_record.features:
            #print(feat)
            fmin = int(feat.location.start)
            fmax = int(feat.location.end)

            if feat.location.strand == 1:
                strand = '+'
            elif feat.location.strand == -1:
                strand = '-'
            else:
                raise Exception("ERROR: unstranded feature encountered: {0}".format(feat))

            #print("{0} located at {1}-{2} strand:{3}".format( locus_tag, fmin, fmax, strand ) )
            if feat.type == 'source':
                continue
            
            if feat.type == 'gene':
                # print the previous gene (if there is one)
                if current_gene is not None:
                    gene.print_as(fh=ofh, source='GenBank', format='gff3')
                
                locus_tag = feat.qualifiers['locus_tag'][0]
                gene = biothings.Gene( id=locus_tag )
                gene.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                current_gene = gene
                current_RNA = None

            elif feat.type == 'mRNA':
                locus_tag = feat.qualifiers['locus_tag'][0]
                rna_count_by_gene[locus_tag] += 1
                feat_id = "{0}.mRNA.{1}".format( locus_tag, rna_count_by_gene[locus_tag] )
                
                mRNA = biothings.mRNA( id=feat_id, parent=current_gene )
                mRNA.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                gene.add_mRNA(mRNA)
                current_RNA = mRNA

                if feat_id in exon_count_by_RNA:
                    raise Exception( "ERROR: two different RNAs found with same ID: {0}".format(feat_id) )
                else:
                    exon_count_by_RNA[feat_id] = 0

            elif feat.type == 'tRNA':
                locus_tag = feat.qualifiers['locus_tag'][0]
                rna_count_by_gene[locus_tag] += 1
                feat_id = "{0}.tRNA.{1}".format( locus_tag, rna_count_by_gene[locus_tag] )
                
                tRNA = biothings.tRNA( id=feat_id, parent=current_gene )
                tRNA.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                gene.add_tRNA(tRNA)
                current_RNA = tRNA

                if feat_id in exon_count_by_RNA:
                    raise Exception( "ERROR: two different RNAs found with same ID: {0}".format(feat_id) )
                else:
                    exon_count_by_RNA[feat_id] = 0

            elif feat.type == 'rRNA':
                locus_tag = feat.qualifiers['locus_tag'][0]
                rna_count_by_gene[locus_tag] += 1
                feat_id = "{0}.rRNA.{1}".format( locus_tag, rna_count_by_gene[locus_tag] )
                
                rRNA = biothings.rRNA( id=feat_id, parent=current_gene )
                rRNA.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                gene.add_rRNA(rRNA)
                current_RNA = rRNA

                if feat_id in exon_count_by_RNA:
                    raise Exception( "ERROR: two different RNAs found with same ID: {0}".format(feat_id) )
                else:
                    exon_count_by_RNA[feat_id] = 0
            
            elif feat.type == 'CDS':
                locus_tag = feat.qualifiers['locus_tag'][0]
                # If processing a prokaryotic GBK, we'll encounter CDS before mRNA, so we have to
                #  manually make one
                if current_RNA is None:
                    feat_id = "{0}.mRNA.{1}".format( locus_tag, rna_count_by_gene[locus_tag] )
                    mRNA = biothings.mRNA( id=feat_id, parent=current_gene )
                    mRNA.locate_on( target=current_assembly, fmin=fmin, fmax=fmax, strand=strand )
                    gene.add_mRNA(mRNA)
                    current_RNA = mRNA
                
                exon_count_by_RNA[current_RNA.id] += 1
                cds_id = "{0}.CDS.{1}".format( current_RNA.id, exon_count_by_RNA[current_RNA.id] )
                current_CDS_phase = 0
                
                for loc in feat.location.parts:
                    subfmin = int(loc.start)
                    subfmax = int(loc.end)
                    
                    CDS = biothings.CDS( id=cds_id, parent=current_RNA )
                    CDS.locate_on( target=current_assembly, fmin=subfmin, fmax=subfmax, strand=strand, phase=current_CDS_phase )
                    current_RNA.add_CDS(CDS)

                    # calculate the starting phase for the next CDS feature (in case there is one)
                    # 0 + 6 = 0     TTGCAT
                    # 0 + 7 = 2     TTGCATG
                    # 1 + 6 = 1     TTGCAT
                    # 2 + 7 = 1     TTGCATG
                    # general: 3 - ((length - previous phase) % 3)
                    current_CDS_phase = 3 - (((subfmax - subfmin) - current_CDS_phase) % 3)
                    if current_CDS_phase == 3:
                        current_CDS_phase = 0

                    exon_id = "{0}.exon.{1}".format( current_RNA.id, exon_count_by_RNA[current_RNA.id] )
                    exon = biothings.Exon( id=exon_id, parent=current_RNA )
                    exon.locate_on( target=current_assembly, fmin=subfmin, fmax=subfmax, strand=strand )
                    current_RNA.add_exon(exon)
                    exon_count_by_RNA[current_RNA.id] += 1
                
            else:
                print("WARNING: The following feature was skipped:\n{0}".format(feat))
                features_skipped_count += 1

        # don't forget to do the last gene, if there were any
        if current_gene is not None:
            gene.print_as(fh=ofh, source='GenBank', format='gff3')

    if args.fasta is True:
        if seqs_pending_writes is True:
            ofh.write("##FASTA\n")
            for assembly_id in assemblies:
                ofh.write(">{0}\n".format(assembly_id))
                ofh.write("{0}\n".format(biocodeutils.wrapped_fasta(assemblies[assembly_id].residues)))

    if features_skipped_count > 0:
        print("Warning: {0} unsupported feature types were skipped".format(features_skipped_count))
        #print("Processing feature: ({0})".format(feat_id))

        if cols[6] == '-':
            strand = -1
        elif cols[6] == '+':
            strand = 1
        else:
            strand = 0

        if cols[2] == 'gene':
            if last_gene is not None:
                print("\n")
                pprint ("DEBUG: last gene was ({0}): {1}".format(last_gene.id, vars(last_gene)))
            
            gene = biothings.Gene(id=feat_id)
            gene.locate_on(target=current_assembly, fmin=rfmin, fmax=rfmax, strand=rstrand)
            print("DEBUG: locating gene {0} on {1} at coordinates fmin:{2}-fmax:{3} strand:{4}".format(feat_id, mol_id, rfmin, rfmax, rstrand) )
            features[feat_id] = gene
            current_assembly.add_gene(gene)

            last_gene = gene
        
        elif cols[2] == 'mRNA':
            mRNA = biothings.mRNA(id=feat_id, parent=parent_feat)
            mRNA.locate_on(target=current_assembly, fmin=rfmin, fmax=rfmax, strand=rstrand)
            print("DEBUG: attaching mRNA:{0} to parent gene:{1}".format(feat_id, parent_feat.id) )
            parent_feat.add_mRNA(mRNA)
            features[feat_id] = mRNA

        elif cols[2] == 'rRNA':
def main():
    parser = argparse.ArgumentParser( description='Metagenemark GFF -> GFF3 conversion script')

    ## output file to be written
    parser.add_argument('-i', '--input', type=str, required=True, help='Path to a GFF file created by Metagenemark' )
    parser.add_argument('-o', '--output', type=str, required=True, help='Path to an output file to be created' )
    parser.add_argument('-p', '--prefix', type=str, required=True, help='Prefix to use in ID generation')
    args = parser.parse_args()

    assemblies = dict()
    current_assembly = None
    
    gene = None
    mRNAs = dict()
    current_sequence = None
    current_gene_comment_lines = list()

    fout = open(args.output, mode='wt', encoding='utf-8')
    fout.write("##gff-version 3\n")

    for line in open(args.input):
        if line.startswith("#"):
            current_gene_comment_lines.append(line)

        else:
            cols = line.split("\t")

            if len(cols) != 9:
                continue

            mol_id = cols[0]
            mol_id_m = re.match('^(\S+) ', mol_id)

            if mol_id_m:
                print("MATCH!")
                mol_id = mol_id_m.group(1)
            
            feat_type = cols[2]

            ## we expect only gene types here
            if feat_type not in ['gene', 'CDS']:
                raise Exception("ERROR: expected only 'gene' or 'CDS' feature types as input (depending on metagenemark version).")

            m_gene = re.match('gene_id[ =](\d+)', cols[8])

            if m_gene:
                gene_num = m_gene.group(1)
            else:
                raise Exception("ERROR: expected 9th column to have gene ids like: gene_id 5")

            ## initialize this assembly if we haven't seen it yet
            if mol_id not in assemblies:
                assemblies[mol_id] = biothings.Assembly( id=mol_id )

            current_assembly = assemblies[mol_id]

            gene = biothings.Gene( id="{0}.gene.{1}".format(args.prefix, gene_num) )
            gene.locate_on( target=current_assembly, fmin=int(cols[3]) - 1, fmax=int(cols[4]), strand=cols[6] )

            mRNA = biothings.mRNA( id="{0}.mRNA.{1}".format(args.prefix, gene_num), parent=gene.id )
            mRNA.locate_on( target=current_assembly, fmin=int(cols[3]) - 1, fmax=int(cols[4]), strand=cols[6] )
            gene.add_mRNA(mRNA)

            CDS = biothings.CDS( id="{0}.CDS.{1}".format(args.prefix, gene_num), parent=mRNA.id )
            CDS.locate_on( target=current_assembly, fmin=int(cols[3]) - 1, fmax=int(cols[4]), strand=cols[6], phase=int(cols[7]) )
            mRNA.add_CDS(CDS)

            exon = biothings.Exon( id="{0}.exon.{1}".format(args.prefix, gene_num), parent=mRNA.id )
            exon.locate_on( target=current_assembly, fmin=int(cols[3]) - 1, fmax=int(cols[4]), strand=cols[6] )
            mRNA.add_exon(exon)

            gene.print_as(fh=fout, source='GeneMark.hmm', format='gff3')
            fout.write( "".join(current_gene_comment_lines) )
            current_gene_comment_lines = list()
Exemplo n.º 14
0
def main():
    parser = argparse.ArgumentParser(
        description=
        'Convert native (GTF) or GFF output from Augustus into GFF3 format')

    ## output file to be written
    parser.add_argument('-i',
                        '--input',
                        type=str,
                        required=True,
                        help='Path to a GFF file created by Augustus')
    parser.add_argument('-o',
                        '--output',
                        type=str,
                        required=True,
                        help='Path to an output file to be created')
    args = parser.parse_args()

    assemblies = dict()
    current_assembly = None

    gene = None
    mRNAs = dict()
    in_sequence = False
    current_sequence = None
    current_gene_comment_lines = list()

    ## Used for tracking the exon count for each gene (for ID purposes)
    exon_count_by_mRNA = dict()

    fout = open(args.output, mode='wt', encoding='utf-8')
    fout.write("##gff-version 3\n")

    for line in open(args.input):
        if line.startswith("#"):
            current_gene_comment_lines.append(line)

            if line.startswith("# end gene "):
                ## purge the comments, then write the gene
                fout.write("".join(current_gene_comment_lines))
                gene.print_as(fh=fout, source='AUGUSTUS', format='gff3')

                gene = None
                mRNAs = dict()
                in_sequence = False
                current_sequence = None
                current_gene_comment_lines = list()

            elif line.startswith("# protein sequence = ["):
                pass
            elif in_sequence is True:
                # build 'current_sequence'
                pass

        else:
            cols = line.split("\t")

            if len(cols) != 9:
                continue

            mol_id = cols[0]
            feat_type = cols[2]

            if feat_type not in ['gene', 'transcript', 'CDS']:
                continue

            ## The output format is GTF by default and (mostly) GFF if the --gff option is used.
            #   If GTF is detected, let's start by transforming the 9th column into GFF so the
            #   libraries can use it
            #   g1  ->  ID=g1
            #   g1.t1  ->  ID=g1.t1;Parent=g1
            #   transcript_id "g1.t1"; gene_id "g1";  ->  ID=g1.t1.cds;Parent=g1.t1
            m_gene = re.match('(g\d+)', cols[8])
            m_transcript = re.match('((g\d+).t\d+)', cols[8])
            m_CDS = re.match('transcript_id "(g\d+.t\d+)"; gene_id "g\d+";',
                             cols[8])

            # the input can be in GTF or GFF.  We need to reformat the 9th column for the GTF entries
            if not cols[8].startswith('ID') and not cols[8].startswith(
                    'Parent'):
                if feat_type == 'gene':
                    if m_gene:
                        cols[8] = "ID={0}".format(m_gene.group(1))
                    else:
                        raise Exception(
                            "ERROR: GTF detected but gene row has bad 9th column format: {0}"
                            .format(cols[8]))
                elif feat_type == 'transcript':
                    if m_transcript:
                        cols[8] = "ID={0};Parent={1}".format(
                            m_transcript.group(1), m_transcript.group(2))
                    else:
                        raise Exception(
                            "ERROR: GTF detected but transcript row has bad 9th column format: {0}"
                            .format(cols[8]))
                elif feat_type == 'CDS':
                    if m_CDS:
                        cols[8] = "ID={0}.cds;Parent={0}".format(
                            m_CDS.group(1))
                    else:
                        raise Exception(
                            "ERROR: GTF detected but CDS row has bad 9th column format: {0}"
                            .format(cols[8]))

            feat_id = biocodegff.column_9_value(cols[8], 'ID')

            ## initialize this assembly if we haven't seen it yet
            if mol_id not in assemblies:
                assemblies[mol_id] = biothings.Assembly(id=mol_id)

            current_assembly = assemblies[mol_id]

            if feat_type == "gene":
                gene = biothings.Gene(id=feat_id)
                gene.locate_on(target=current_assembly,
                               fmin=int(cols[3]) - 1,
                               fmax=int(cols[4]),
                               strand=cols[6])

            elif feat_type == "transcript":
                mRNA = biothings.mRNA(id=feat_id, parent=gene)
                mRNA.locate_on(target=current_assembly,
                               fmin=int(cols[3]) - 1,
                               fmax=int(cols[4]),
                               strand=cols[6])
                gene.add_mRNA(mRNA)
                mRNAs[mRNA.id] = mRNA

                if feat_id in exon_count_by_mRNA:
                    raise Exception(
                        "ERROR: two different mRNAs found with same ID: {0}".
                        format(feat_id))
                else:
                    exon_count_by_mRNA[feat_id] = 0

            elif feat_type == "CDS":
                parent_id = biocodegff.column_9_value(cols[8], 'Parent')

                ## sanity check that we've seen this parent
                if parent_id not in mRNAs:
                    raise Exception(
                        "ERROR: Found CDS column with parent ({0}) mRNA not yet in the file"
                        .format(parent_id))

                CDS = biothings.CDS(id=feat_id, parent=mRNAs[parent_id])
                CDS.locate_on(target=current_assembly,
                              fmin=int(cols[3]) - 1,
                              fmax=int(cols[4]),
                              strand=cols[6],
                              phase=int(cols[7]))
                mRNA.add_CDS(CDS)

                ## exons weren't explicitly defined in the input file, so we need to derive new IDs for them
                exon_count_by_mRNA[parent_id] += 1
                exon_id = "{0}.exon{1}".format(parent_id,
                                               exon_count_by_mRNA[parent_id])

                exon = biothings.Exon(id=exon_id, parent=mRNAs[parent_id])
                exon.locate_on(target=current_assembly,
                               fmin=int(cols[3]) - 1,
                               fmax=int(cols[4]),
                               strand=cols[6])
                mRNA.add_exon(exon)