/ 
bioperl-1.4
/ Bio::SeqFeature::Collection

NAME

Bio::SeqFeature::Collection - A container class for SeqFeatures suitable for performing operations such as finding features within a range, that match a certain feature type, etc.

SYNOPSIS

use Bio::SeqFeature::Collection;
use Bio::Location::Simple;
use Bio::Tools::GFF;
use Bio::Root::IO;
# let's first input some features
my $gffio = Bio::Tools::GFF->new(-file => Bio::Root::IO->catfile
				 ("t","data","myco_sites.gff"),
				 -gff_version => 2);
my @features = ();
# loop over the input stream
while(my $feature = $gffio->next_feature()) {
    # do something with feature
    push @features, $feature;
}
$gffio->close();
# build the Collection object
my $col = new Bio::SeqFeature::Collection();
# add these features to the object
my $totaladded = $col->add_features(\@features);

my @subset = $col->features_in_range(-start => 1,
				     -end => 25000,
				     -strand => 1,
				     -contain => 0);
# subset should have 18 entries for this dataset
print "size is ", scalar @subset, "\n";
@subset = $col->features_in_range(-range => Bio::Location::Simple->new
				  (-start => 70000,
				   -end => 150000,
				   -strand => -1),
				  -contain => 1,
				  -strandmatch => 'strong');

# subset should have 22 entries for this dataset
print "size is ", scalar @subset, "\n";
print "total number of features in collection is ",
       $col->feature_count(),"\n";

DESCRIPTION

This object will efficiently allow one for query subsets of ranges within a large collection of sequence features (in fact the objects just have to be Bio::RangeI compliant). This is done by the creation of bins which are stored in order in a B-Tree data structure as provided by the DB_File interface to the Berkeley DB.

This is based on work done by Lincoln for storage in a mysql instance - this is intended to be an embedded in-memory implementation for easily quering for subsets of a large range set.

Collections can be made persistant by keeping the indexfile and passing in the -keep flag like this:

my $collection = new Bio::SeqFeature::Collection(-keep => 1,
                                                 -file => 'col.idx');
$collaction->add_features(\@features);
undef $collection;

# To reuse this collection, next time you initialize a Collection object
# specify the filename and the index will be reused.
$collection = new Bio::SeqFeature::Collection(-keep => 1,
                                              -file => 'col.idx');

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 the Bioperl mailing list. Your participation is much appreciated.

bioperl-l@bioperl.org              - General discussion
http://bioperl.org/MailList.shtml  - About the mailing lists

Reporting Bugs

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

http://bugzilla.bioperl.org/

AUTHOR - Jason Stajich

Email jason@bioperl.org

CONTRIBUTORS

Using code and strategy developed by Lincoln Stein (lstein@cshl.org) in Bio::DB::GFF implementation. Credit also to Lincoln for suggesting using Storable to serialize features rather than my previous implementation which kept the features in memory.

APPENDIX

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

new

Title   : new
Usage   : my $obj = new Bio::SeqFeature::Collection();
Function: Builds a new Bio::SeqFeature::Collection object
Returns : Bio::SeqFeature::Collection
Args    :

          -minbin        minimum value to use for binning
                         (default is 100,000,000)
          -maxbin        maximum value to use for binning
                         (default is 1,000)
          -file          filename to store/read the
                         BTREE from rather than an in-memory structure
                         (default is false and in-memory).
          -keep          boolean, will not remove index file on
                         object destruction.
          -features      Array ref of features to add initially

add_features

Title   : add_features
Usage   : $collection->add_features(\@features);
Function:
Returns : number of features added
Args    : arrayref of Bio::SeqFeatureI objects to index

features_in_range

 Title   : features_in_range
 Usage   : my @features = $collection->features_in_range($range)
 Function: Retrieves a list of features which were contained or overlap the
           the requested range (see Args for way to specify overlap or
				only those containe)d
 Returns : List of Bio::SeqFeatureI objects
 Args    : -range => Bio::RangeI object defining range to search,
           OR
           -start  => start,
           -end    => end,
           -strand  => strand

           -contain => boolean - true if feature must be completely
                       contained with range
                       OR false if should include features that simply overlap
                       the range. Default: true.
           -strandmatch =>  'strong',  ranges must have the same strand
                            'weak',    ranges must have the same
                                           strand or no strand
                            'ignore', ignore strand information
                           Default. 'ignore'.

remove_features

 Title   : remove_features
 Usage   : $collection->remove_features(\@array)
 Function: Removes the requested sequence features (based on features
	   which have the same location)
 Returns : Number of features removed
 Args    : Arrayref of Bio::RangeI objects

get_all_features

Title   : get_all_features
Usage   : my @f = $col->get_all_features()
Function: Return all the features stored in this collection (Could be large)
Returns : Array of Bio::RangeI objects
Args    : None

min_bin

Title   : min_bin
Usage   : my $minbin= $self->min_bin;
Function: Get/Set the minimum value to use for binning
Returns : integer
Args    : [optional] minimum bin value

max_bin

Title   : max_bin
Usage   : my $maxbin= $self->max_bin;
Function: Get/Set the maximum value to use for binning
Returns : integer
Args    : [optional] maximum bin value

feature_count

Title   : feature_count
Usage   : my $c = $col->feature_count()
Function: Retrieve the total number of features in the collection
Returns : integer
Args    : none

indexfile

Title   : indexfile
Usage   : $obj->indexfile($newval)
Function: Get/set the filename where index is kept
Returns : value of indexfile (a filename string)
Args    : on set, new value (a filename string )

keep

Title   : keep
Usage   : $obj->keep($newval)
Function: Get/set boolean flag to keep the indexfile after
          exiting program
Example :
Returns : value of keep (boolean)
Args    : on set, new value (boolean)