Bio::Tools::GFF(3)

NAME
Bio::Tools::GFF - A Bio::SeqAnalysisParserI compliant GFF format parser

SYNOPSIS
    use Bio::Tools::GFF;

    # specify input via -fh or -file
    my $gffio = Bio::Tools::GFF->new(-fh => \*STDIN, -gff_version => 2);
    my $feature;
    # loop over the input stream
    while($feature = $gffio->next_feature()) {
        # do something with feature
    }
    $gffio->close();

    # you can also obtain a GFF parser as a SeqAnalasisParserI in
    # HT analysis pipelines (see Bio::SeqAnalysisParserI and
    # Bio::Factory::SeqAnalysisParserFactory)
    my $factory = Bio::Factory::SeqAnalysisParserFactory->new();
    my $parser = $factory->get_parser(-input => \*STDIN, -method => "gff");
    while($feature = $parser->next_feature()) {
        # do something with feature
    }

DESCRIPTION
This class provides a simple GFF parser and writer. In the sense of a SeqAnalysisParser, it parses an input file or stream into SeqFeatureI objects, but is not in any way specific to a particular analysis program and the output that program produces.

That is, if you can get your analysis program spit out GFF, here is your result parser.

GFF3 AND SEQUENCE DATA
GFF3 supports sequence data; see

http://www.sequenceontology.org/gff3.shtml

There are a number of ways to deal with this -

If you call

  $gffio->ignore_sequence(1)

prior to parsing the sequence data is ignored; this is useful if you just want the features. It avoids the memory overhead in building and caching sequences

Alternatively, you can call either

  $gffio->get_seqs()

Or

  $gffio->seq_id_by_h()

At the end of parsing to get either a list or hashref of Bio::Seq objects (see the documentation for each of these methods)

Note that these objects will not have the features attached - you have to do this yourself, OR call

  $gffio->features_attached_to_seqs(1)

PRIOR to parsing; this will ensure that the Seqs have the features attached; ie you will then be able to call

  $seq->get_SeqFeatures();

And use Bio::SeqIO methods

Note that auto-attaching the features to seqs will incur a higher memory overhead as the features must be cached until the sequence data is found

TODO
Make a Bio::SeqIO class specifically for GFF3 with sequence data

FEEDBACK

  Mailing Lists
User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to one of the Bioperl mailing lists. Your participation is much appreciated.

  bioperl-l@bioperl.org                  - General discussion
  http://bioperl.org/wiki/Mailing_lists  - About the mailing lists

  Support
Please direct usage questions or support issues to the mailing list:

bioperl-l@bioperl.org

rather than to the module maintainer directly. Many experienced and reponsive experts will be able look at the problem and quickly address it. Please include a thorough description of the problem with code and data examples if at all possible.

  Reporting Bugs
Report bugs to the Bioperl bug tracking system to help us keep track the bugs and their resolution. Bug reports can be submitted the web:

  https://github.com/bioperl/bioperl-live/issues

AUTHOR - Matthew Pocock
Email mrp-at-sanger.ac.uk

CONTRIBUTORS
Jason Stajich, jason-at-biperl-dot-org Chris Mungall, cjm-at-fruitfly-dot-org Steffen Grossmann [SG], grossman at molgen.mpg.de Malcolm Cook, mec-at-stowers-institute.org

APPENDIX
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _

  new
 Title   : new
 Usage   : my $parser = Bio::Tools::GFF->new(-gff_version => 2,
                                             -file        => "filename.gff");
           or
           my $writer = Bio::Tools::GFF->new(-gff_version => 3,
                                             -file        => ">filename.gff3");
 Function: Creates a new instance. Recognized named parameters are -file, -fh,
           and -gff_version.
 Returns : a new object
 Args    : named parameters
           -gff_version => [1,2,3]

  _parse_header
 Title   : _parse_header
 Usage   : $gffio->_parse_header()
 Function: used to turn parse GFF header lines.  currently
           produces Bio::LocatableSeq objects from ##sequence-region
           lines
 Returns : 1 on success
 Args    : none

  next_segment
 Title   : next_segment
 Usage   : my $seq = $gffio->next_segment;
 Function: Returns a Bio::LocatableSeq object corresponding to a
           GFF "##sequence-region" header line.
 Example :
 Returns : A Bio::LocatableSeq object, or undef if
           there are no more sequences.
 Args    : none

  next_feature
 Title   : next_feature
 Usage   : $seqfeature = $gffio->next_feature();
 Function: Returns the next feature available in the input file or stream, or
           undef if there are no more features.
 Example :
 Returns : A Bio::SeqFeatureI implementing object, or undef if there are no
           more features.
 Args    : none

  from_gff_string
 Title   : from_gff_string
 Usage   : $gff->from_gff_string($feature, $gff_string);
 Function: Sets properties of a SeqFeatureI object from a GFF-formatted
           string. Interpretation of the string depends on the version
           that has been specified at initialization.

           This method is used by next_feature(). It actually dispatches to
           one of the version-specific (private) methods.
 Example :
 Returns : void
 Args    : A Bio::SeqFeatureI implementing object to be initialized
           The GFF-formatted string to initialize it from

  _from_gff1_string
 Title   : _from_gff1_string
 Usage   :
 Function:
 Example :
 Returns : void
 Args    : A Bio::SeqFeatureI implementing object to be initialized
           The GFF-formatted string to initialize it from

  _from_gff2_string
 Title   : _from_gff2_string
 Usage   :
 Function:
 Example :
 Returns : void
 Args    : A Bio::SeqFeatureI implementing object to be initialized
           The GFF2-formatted string to initialize it from

  write_feature
 Title   : write_feature
 Usage   : $gffio->write_feature($feature);
 Function: Writes the specified SeqFeatureI object in GFF format to the stream
           associated with this instance.
 Returns : none
 Args    : An array of Bio::SeqFeatureI implementing objects to be serialized

  gff_string
 Title   : gff_string
 Usage   : $gffstr = $gffio->gff_string($feature);
 Function: Obtain the GFF-formatted representation of a SeqFeatureI object.
           The formatting depends on the version specified at initialization.

           This method is used by write_feature(). It actually dispatches to
           one of the version-specific (private) methods.
 Example :
 Returns : A GFF-formatted string representation of the SeqFeature
 Args    : A Bio::SeqFeatureI implementing object to be GFF-stringified

  _gff1_string
 Title   : _gff1_string
 Usage   : $gffstr = $gffio->_gff1_string
 Function:
 Example :
 Returns : A GFF1-formatted string representation of the SeqFeature
 Args    : A Bio::SeqFeatureI implementing object to be GFF-stringified

  _gff2_string
 Title   : _gff2_string
 Usage   : $gffstr = $gffio->_gff2_string
 Function:
 Example :
 Returns : A GFF2-formatted string representation of the SeqFeature
 Args    : A Bio::SeqFeatureI implementing object to be GFF2-stringified

  _gff25_string
 Title   : _gff25_string
 Usage   : $gffstr = $gffio->_gff2_string
 Function: To get a format of GFF that is peculiar to Gbrowse/Bio::DB::GFF
 Example :
 Returns : A GFF2.5-formatted string representation of the SeqFeature
 Args    : A Bio::SeqFeatureI implementing object to be GFF2.5-stringified

  _gff3_string
  Title   : _gff3_string
  Usage   : $gffstr = $gffio->_gff3_string
  Function:
  Example :
  Returns : A GFF3-formatted string representation of the SeqFeature
  Args    : A Bio::SeqFeatureI implementing object to be GFF3-stringified

  gff_version
  Title   : _gff_version
  Usage   : $gffversion = $gffio->gff_version
  Function:
  Example :
  Returns : The GFF version this parser will accept and emit.
  Args    : none

  newFh
 Title   : newFh
 Usage   : $fh = Bio::Tools::GFF->newFh(-file=>$filename,-format=>'Format')
 Function: does a new() followed by an fh()
 Example : $fh = Bio::Tools::GFF->newFh(-file=>$filename,-format=>'Format')
           $feature = <$fh>;            # read a feature object
           print $fh $feature;          # write a feature object
 Returns : filehandle tied to the Bio::Tools::GFF class
 Args    :

  fh
 Title   : fh
 Usage   : $obj->fh
 Function:
 Example : $fh = $obj->fh;      # make a tied filehandle
           $feature = <$fh>;    # read a feature object
           print $fh $feature;  # write a feature object
 Returns : filehandle tied to Bio::Tools::GFF class
 Args    : none

  get_seqs
 Title   : get_seqs
 Usage   :
 Function: Returns all Bio::Seq objects populated by GFF3 file
 Example :
 Returns :
 Args    :

  features_attached_to_seqs
 Title   : features_attached_to_seqs
 Usage   : $obj->features_attached_to_seqs(1);
 Function: For use with GFF3 containing sequence only

    Setting this B<before> parsing ensures that all Bio::Seq object
    created will have the appropriate features added to them

    defaults to false (off)

    Note that this mode will incur higher memory usage because features
    will have to be cached until the relevant feature comes along

 Example :
 Returns : value of features_attached_to_seqs (a boolean)
 Args    : on set, new value (a boolean, optional)

  ignore_sequence
 Title   : ignore_sequence
 Usage   : $obj->ignore_sequence(1);
 Function: For use with GFF3 containing sequence only

    Setting this B<before> parsing means that all sequence data will be
    ignored

 Example :
 Returns : value of ignore_sequence (a boolean)
 Args    : on set, new value (a boolean, optional)