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Ace::Sequence::Feature.3pm
Langue: en
Version: 2001-09-17 (mandriva - 01/05/08)
Section: 3 (Bibliothèques de fonctions)
NAME
Ace::Sequence::Feature - Examine Sequence Feature TablesSYNOPSIS
# open database connection and get an Ace::Object sequence use Ace::Sequence; # get a megabase from the middle of chromosome I $seq = Ace::Sequence->new(-name => 'CHROMOSOME_I, -db => $db, -offset => 3_000_000, -length => 1_000_000); # get all the homologies (a list of Ace::Sequence::Feature objs) @homol = $seq->features('Similarity'); # Get information about the first one $feature = $homol[0]; $type = $feature->type; $subtype = $feature->subtype; $start = $feature->start; $end = $feature->end; $score = $feature->score; # Follow the target $target = $feature->info; # print the target's start and end positions print $target->start,'-',$target->end, "\n";
DESCRIPTION
Ace::Sequence::Feature is a subclass of Ace::Sequence::Feature specialized for returning information about particular features in a GFF format feature table.OBJECT CREATION
You will not ordinarily create an Ace::Sequence::Feature object directly. Instead, objects will be created in response to a feature() call to an Ace::Sequence object. If you wish to create an Ace::Sequence::Feature object directly, please consult the source code for the new() method.OBJECT METHODS
Most methods are inherited from Ace::Sequence. The following methods are also supported:- seqname()
-
$object = $feature->seqname;
Return the ACeDB Sequence object that this feature is attached to. The return value is an Ace::Object of the Sequence class. This corresponds to the first field of the GFF format and does not necessarily correspond to the Ace::Sequence object from which the feature was obtained (use source_seq() for that).
- source()
- method()
- subtype()
-
$source = $feature->source;
These three methods are all synonyms for the same thing. They return the second field of the GFF format, called ``source'' in the documentation. This is usually the method or algorithm used to predict the feature, such as ``GeneFinder'' or ``tRNA'' scan. To avoid ambiguity and enhance readability, the method() and subtype() synonyms are also recognized.
- feature()
- type()
-
$type = $feature->type;
These two methods are also synonyms. They return the type of the feature, such as ``exon'', ``similarity'' or ``Predicted_gene''. In the GFF documentation this is called the ``feature'' field. For readability, you can also use type() to fetch the field.
- abs_start()
-
$start = $feature->abs_start;
This method returns the absolute start of the feature within the sequence segment indicated by seqname(). As in the Ace::Sequence method, use start() to obtain the start of the feature relative to its source.
- abs_start()
-
$start = $feature->abs_start;
This method returns the start of the feature relative to the sequence segment indicated by seqname(). As in the Ace::Sequence method, you will more usually use the inherited start() method to obtain the start of the feature relative to its source sequence (the Ace::Sequence from which it was originally derived).
- abs_end()
-
$start = $feature->abs_end;
This method returns the end of the feature relative to the sequence segment indicated by seqname(). As in the Ace::Sequence method, you will more usually use the inherited end() method to obtain the end of the feature relative to the Ace::Sequence from which it was derived.
- score()
-
$score = $feature->score;
For features that are associated with a numeric score, such as similarities, this returns that value. For other features, this method returns undef.
- strand()
-
$strand = $feature->strand;
Returns the strandedness of this feature, either ``+1'' or ``-1''. For features that are not stranded, returns 0.
- reversed()
-
$reversed = $feature->reversed;
Returns true if the feature is reversed relative to its source sequence.
- frame()
-
$frame = $feature->frame;
For features that have a frame, such as a predicted coding sequence, returns the frame, either 0, 1 or 2. For other features, returns undef.
- group()
- info()
- target()
-
$info = $feature->info;
These methods (synonyms for one another) return an Ace::Object containing other information about the feature derived from the 8th field of the GFF format, the so-called ``group'' field. The type of the Ace::Object is dependent on the nature of the feature. The possibilities are shown in the table below:
Feature Type Value of Group Field ------------ -------------------- note A Text object containing the note. similarity An Ace::Sequence::Homology object containing the target and its start/stop positions. intron An Ace::Object containing the gene from exon which the feature is derived. misc_feature other A Text object containing the group data.
- asString()
-
$label = $feature->asString;
Returns a human-readable identifier describing the nature of the feature. The format is:
$type:$name/$start-$end
for example:
exon:ZK154.3/1-67
This method is also called automatically when the object is treated in a string context.
SEE ALSO
Ace, Ace::Object, Ace::Sequence,Ace::Sequence::Homol, Ace::Sequence::FeatureList, GFFAUTHOR
Lincoln Stein <lstein@cshl.org> with extensive help from Jean Thierry-Mieg <mieg@kaa.crbm.cnrs-mop.fr>Copyright (c) 1999, Lincoln D. Stein
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See DISCLAIMER.txt for disclaimers of warranty.
Contenus ©2006-2024 Benjamin Poulain
Design ©2006-2024 Maxime Vantorre