/ 
bioperl-1.5.2_005-RCb
/ Bio::Tools::GFF

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

[added by cjm 2004/07/09]

GFF3 supports sequence data; see http://song.sourceforge.net/gff3-jan04.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

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:

http://bugzilla.open-bio.org/

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

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 = new Bio::Tools::GFF(-gff_version => 2,
					    -file        => "filename.gff");
           or
           my $writer = new Bio::Tools::GFF(-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 containg 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 containg 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)