Bio DasI
SummaryIncluded librariesPackage variablesSynopsisDescriptionGeneral documentationMethods
WebCvsRaw content
Bio::DasI - DAS-style access to a feature database
Package variables
No package variables defined.
Included modules
Bio::Root::RootI Bio::SeqFeature::CollectionI
  # Open up a feature database somehow...
$db = Bio::DasI->new(@args);
@segments = $db->segment(-name => 'NT_29921.4', -start => 1, -end => 1000000); # segments are Bio::Das::SegmentI - compliant objects # fetch a list of features @features = $db->features(-type=>['type1','type2','type3']); # invoke a callback over features $db->features(-type=>['type1','type2','type3'], -callback => sub { ... } ); $stream = $db->get_seq_stream(-type=>['type1','type2','type3']); while (my $feature = $stream->next_seq) { # each feature is a Bio::SeqFeatureI-compliant object } # get all feature types @types = $db->types; # count types %types = $db->types(-enumerate=>1); @feature = $db->get_feature_by_name($class=>$name); @feature = $db->get_feature_by_target($target_name); @feature = $db->get_feature_by_attribute($att1=>$value1,$att2=>$value2); $feature = $db->get_feature_by_id($id); $error = $db->error;
Bio::DasI is a simplified alternative interface to sequence annotation
databases used by the distributed annotation system (see
Bio::Das). In this scheme, the genome is represented as a series of
features, a subset of which are named. Named features can be used as
reference points for retrieving "segments" (see Bio::Das::SegmentI),
and these can, in turn, be used as the basis for exploring the genome
In addition to a name, each feature has a "class", which is
essentially a namespace qualifier and a "type", which describes what
type of feature it is. Das uses the GO consortium's ontology of
feature types, and so the type is actually an object of class
Bio::Das::FeatureTypeI (see Bio::Das::FeatureTypeI). Bio::DasI
provides methods for interrogating the database for the types it
contains and the counts of each type.
No description
Methods description
featurescode    nextTop
 Title   : features
Usage : $db->features(@args)
Function: get all features, possibly filtered by type
Returns : a list of Bio::SeqFeatureI objects
Args : see below
Status : public
This routine will retrieve features in the database regardless of
position. It can be used to return all features, or a subset based on
their type
Arguments are -option=>value pairs as follows:
  -types     List of feature types to return.  Argument is an array
of Bio::Das::FeatureTypeI objects or a set of strings
that can be converted into FeatureTypeI objects.
-callback A callback to invoke on each feature. The subroutine will be passed each Bio::SeqFeatureI object in turn. -attributes A hash reference containing attributes to match.
The -attributes argument is a hashref containing one or more attributes
to match against:
  -attributes => { Gene => 'abc-1',
Note => 'confirmed' }
Attribute matching is simple exact string matching, and multiple
attributes are ANDed together. See Bio::DB::ConstraintsI for a
more sophisticated take on this.
If one provides a callback, it will be invoked on each feature in
turn. If the callback returns a false value, iteration will be
interrupted. When a callback is provided, the method returns undef.
 Title   : get_feature_by_attribute
Usage : $db->get_feature_by_attribute(attribute1=>value1,attribute2=>value2)
Function: fetch features by combinations of attribute values
Returns : a list of Bio::SeqFeatureI objects
Args : the class and name of the desired feature
Status : public
This method can be used to fetch a set of features from the database.
Attributes are a list of name=>value pairs. They will be
logically ANDed together. If an attribute value is an array
reference, the list of values in the array is treated as an
alternative set of values to be ORed together.
 Title   : get_feature_by_id
Usage : $db->get_feature_by_target($id)
Function: fetch a feature by its ID
Returns : a Bio::SeqFeatureI objects
Args : the ID of the feature
Status : public
If the database provides unique feature IDs, this can be used to
retrieve a single feature from the database. If not overridden, this
interface calls get_feature_by_name() and returns the first element.
 Title   : get_feature_by_name
Usage : $db->get_feature_by_name(-class=>$class,-name=>$name)
Function: fetch features by their name
Returns : a list of Bio::SeqFeatureI objects
Args : the class and name of the desired feature
Status : public
This method can be used to fetch named feature(s) from the database.
The -class and -name arguments have the same meaning as in segment(),
and the method also accepts the following short-cut forms:
  1) one argument: the argument is treated as the feature name
2) two arguments: the arguments are treated as the class and name
(note: this uses _rearrange() so the first argument must not
begin with a hyphen or it will be interpreted as a named
This method may return zero, one, or several Bio::SeqFeatureI objects.
The implementor may allow the name to contain wildcards, in which case
standard C-shell glob semantics are expected.
 Title   : get_feature_by_target
Usage : $db->get_feature_by_target($class => $name)
Function: fetch features by their similarity target
Returns : a list of Bio::SeqFeatureI objects
Args : the class and name of the desired feature
Status : public
This method can be used to fetch a named feature from the database
based on its similarity hit. The arguments are the same as
get_feature_by_name(). If this is not implemented, the interface
defaults to using get_feature_by_name().
 Title   : get_seq_stream
Usage : $seqio = $db->get_seq_stream(@args)
Function: Performs a query and returns an iterator over it
Returns : a Bio::SeqIO stream capable of returning Bio::SeqFeatureI objects
Args : As in features()
Status : public
This routine takes the same arguments as features(), but returns a
Bio::SeqIO::Stream-compliant object. Use it like this:
  $stream = $db->get_seq_stream('exon');
while (my $exon = $stream->next_seq) {
print $exon,"\n";
NOTE: In the interface this method is aliased to get_feature_stream(),
as the name is more descriptive.
 Title   : new
Usage : Bio::DasI->new(@args)
Function: Create new Bio::DasI object
Returns : a Bio::DasI object
Args : see below
The new() method creates a new object. The argument list is either a
single argument consisting of a connection string, or the following
list of -name=>value arguments:
   Argument        Description
-------- -----------
-dsn Connection string for database -adaptor Name of an adaptor class to use when connecting -aggregator Array ref containing list of aggregators "semantic mappers" to apply to database -user Authentication username -pass Authentication password
Implementors of DasI may add other arguments.
 Title   : refclass
Usage : $class = $db->refclass
Function: returns the default class to use for segment() calls
Returns : a string
Args : none
Status : public
For data sources which use namespaces to distinguish reference
sequence accessions, this returns the default namespace (or "class")
to use. This interface defines a default of "Accession".
 Title   : search_notes
Usage : $db->search_notes($search_term,$max_results)
Function: full-text search on features, ENSEMBL-style
Returns : an array of [$name,$description,$score]
Args : see below
Status : public
This routine performs a full-text search on feature attributes (which
attributes depend on implementation) and returns a list of
[$name,$description,$score], where $name is the feature ID,
$description is a human-readable description such as a locus line, and
$score is the match strength.
Since this is a decidedly non-standard thing to do (but the generic
genome browser uses it), the default method returns an empty list.
You do not have to implement it.
 Title   : segment
Usage : $db->segment(@args);
Function: create a segment object
Returns : segment object(s)
Args : see below
This method generates a Bio::Das::SegmentI object (see
Bio::Das::SegmentI). The segment can be used to find overlapping
features and the raw sequence.
When making the segment() call, you specify the ID of a sequence
landmark (e.g. an accession number, a clone or contig), and a
positional range relative to the landmark. If no range is specified,
then the entire region spanned by the landmark is used to generate the
Arguments are -option=>value pairs as follows:
 -name         ID of the landmark sequence.
-class A namespace qualifier. It is not necessary for the database to honor namespace qualifiers, but if it does, this is where the qualifier is indicated. -version Version number of the landmark. It is not necessary for the database to honor versions, but if it does, this is where the version is indicated. -start Start of the segment relative to landmark. Positions follow standard 1-based sequence rules. If not specified, defaults to the beginning of the landmark. -end End of the segment relative to the landmark. If not specified, defaults to the end of the landmark.
The return value is a list of Bio::Das::SegmentI objects. If the method
is called in a scalar context and there are no more than one segments
that satisfy the request, then it is allowed to return the segment.
Otherwise, the method must throw a "multiple segment exception".
 Title   : types
Usage : $db->types(@args)
Function: return list of feature types in database
Returns : a list of Bio::Das::FeatureTypeI objects
Args : see below
This routine returns a list of feature types known to the database. It
is also possible to find out how many times each feature occurs.
Arguments are -option=>value pairs as follows:
  -enumerate  if true, count the features
The returned value will be a list of Bio::Das::FeatureTypeI objects
(see Bio::Das::FeatureTypeI.
If -enumerate is true, then the function returns a hash (not a hash
reference) in which the keys are the stringified versions of
Bio::Das::FeatureTypeI and the values are the number of times each
feature appears in the database.
Methods code
sub features {
sub get_feature_by_attribute {
sub get_feature_by_id {
sub get_feature_by_name {
sub get_feature_by_target {
sub get_feature_stream {
sub get_seq_stream {
sub new {
sub refclass {
sub search_notes {
sub segment {
sub types {
General documentation
Mailing ListsTop
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.
Reporting BugsTop
Report bugs to the Bioperl bug tracking system to help us keep track
the bugs and their resolution. Bug reports can be submitted via email
or the web:
AUTHOR - Lincoln SteinTop
The rest of the documentation details each of the object
methods. Internal methods are usually preceded with a _