SYNOPSIS
# Bio::PrimarySeqI is the interface class for sequences.
# If you are a newcomer to bioperl, you might want to start with
# Bio::Seq documentation.
# Test if this is a seq object
$obj->isa("Bio::PrimarySeqI") ||
$obj->throw("$obj does not implement the Bio::PrimarySeqI interface");
# Accessors
$string = $obj->seq();
$substring = $obj->subseq(12,50);
$display = $obj->display_id(); # for human display
$id = $obj->primary_id(); # unique id for this object,
# implementation defined
$unique_key= $obj->accession_number(); # unique biological id
# Object manipulation
eval {
$rev = $obj->revcom();
};
if( $@ ) {
$obj->throw( "Could not reverse complement. ".
"Probably not DNA. Actual exception\n$@\n" );
}
$trunc = $obj->trunc(12,50);
# $rev and $trunc are Bio::PrimarySeqI compliant objects
DESCRIPTION
This object defines an abstract interface to basic sequence information - for most users of the package the documentation (and methods) in this class are not useful - this is a developers-only class which defines what methods have to be implmented by other Perl objects to comply to the Bio::PrimarySeqI interface. Go ``perldoc Bio::Seq'' or ``man Bio::Seq'' for more information on the main class for sequences.PrimarySeq is an object just for the sequence and its name(s), nothing more. Seq is the larger object complete with features. There is a pure perl implementation of this in Bio::PrimarySeq. If you just want to use Bio::PrimarySeq objects, then please read that module first. This module defines the interface, and is of more interest to people who want to wrap their own Perl Objects/RDBs/FileSystems etc in way that they ``are'' bioperl sequence objects, even though it is not using Perl to store the sequence etc.
This interface defines what bioperl considers necessary to ``be'' a sequence, without providing an implementation of this, an implementation is provided in Bio::PrimarySeq. If you want to provide a Bio::PrimarySeq-compliant object which in fact wraps another object/database/out-of-perl experience, then this is the correct thing to wrap, generally by providing a wrapper class which would inherit from your object and this Bio::PrimarySeqI interface. The wrapper class then would have methods lists in the ``Implementation Specific Functions'' which would provide these methods for your object.
FEEDBACK
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Please direct usage questions or support issues to the mailing list: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
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AUTHOR - Ewan Birney
Email [email protected]APPENDIX
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _Implementation-specific Functions
These functions are the ones that a specific implementation must define.seq
Title : seq
Usage : $string = $obj->seq()
Function: Returns the sequence as a string of letters. The
case of the letters is left up to the implementer.
Suggested cases are upper case for proteins and lower case for
DNA sequence (IUPAC standard), but implementations are suggested to
keep an open mind about case (some users... want mixed case!)
Returns : A scalar
Status : Virtual
subseq
Title : subseq
Usage : $substring = $obj->subseq(10,40);
Function: Returns the subseq from start to end, where the first base
is 1 and the number is inclusive, i.e. 1-2 are the first two
bases of the sequence.
Start cannot be larger than end but can be equal.
Returns : A string
Args :
Status : Virtual
display_id
Title : display_id
Usage : $id_string = $obj->display_id();
Function: Returns the display id, also known as the common name of the Sequence
object.
The semantics of this is that it is the most likely string
to be used as an identifier of the sequence, and likely to
have "human" readability. The id is equivalent to the ID
field of the GenBank/EMBL databanks and the id field of the
Swissprot/sptrembl database. In fasta format, the >(\S+) is
presumed to be the id, though some people overload the id
to embed other information. Bioperl does not use any
embedded information in the ID field, and people are
encouraged to use other mechanisms (accession field for
example, or extending the sequence object) to solve this.
Notice that $seq->id() maps to this function, mainly for
legacy/convenience reasons.
Returns : A string
Args : None
Status : Virtual
accession_number
Title : accession_number
Usage : $unique_biological_key = $obj->accession_number;
Function: Returns the unique biological id for a sequence, commonly
called the accession_number. For sequences from established
databases, the implementors should try to use the correct
accession number. Notice that primary_id() provides the
unique id for the implemetation, allowing multiple objects
to have the same accession number in a particular implementation.
For sequences with no accession number, this method should return
"unknown".
Returns : A string
Args : None
Status : Virtual
primary_id
Title : primary_id
Usage : $unique_implementation_key = $obj->primary_id;
Function: Returns the unique id for this object in this
implementation. This allows implementations to manage their
own object ids in a way the implementaiton can control
clients can expect one id to map to one object.
For sequences with no accession number, this method should
return a stringified memory location.
Returns : A string
Args : None
Status : Virtual
can_call_new
Title : can_call_new
Usage : if( $obj->can_call_new ) {
$newobj = $obj->new( %param );
}
Function: Can_call_new returns 1 or 0 depending
on whether an implementation allows new
constructor to be called. If a new constructor
is allowed, then it should take the followed hashed
constructor list.
$myobject->new( -seq => $sequence_as_string,
-display_id => $id
-accession_number => $accession
-alphabet => 'dna',
);
Returns : 1 or 0
Args :
alphabet
Title : alphabet
Usage : if( $obj->alphabet eq 'dna' ) { /Do Something/ }
Function: Returns the type of sequence being one of
'dna', 'rna' or 'protein'. This is case sensitive.
This is not called "type" because this would cause
upgrade problems from the 0.5 and earlier Seq objects.
Returns : A string either 'dna','rna','protein'. NB - the object must
make a call of the alphabet, if there is no alphabet specified it
has to guess.
Args : None
Status : Virtual
moltype
Title : moltype Usage : Deprecated. Use alphabet() instead.
Implementation-optional Functions
The following functions rely on the above functions. An implementing class does not need to provide these functions, as they will be provided by this class, but is free to override these functions.The revcom(), trunc(), and translate() methods create new sequence objects. They will call new() on the class of the sequence object instance passed as argument, unless can_call_new() returns FALSE. In the latter case a Bio::PrimarySeq object will be created. Implementors which really want to control how objects are created (eg, for object persistence over a database, or objects in a CORBA framework), they are encouraged to override these methods
revcom
Title : revcom
Usage : $rev = $seq->revcom()
Function: Produces a new Bio::PrimarySeqI implementing object which
is the reversed complement of the sequence. For protein
sequences this throws an exception of "Sequence is a
protein. Cannot revcom".
The id is the same id as the original sequence, and the
accession number is also indentical. If someone wants to
track that this sequence has be reversed, it needs to
define its own extensions.
To do an inplace edit of an object you can go:
$seq = $seq->revcom();
This of course, causes Perl to handle the garbage
collection of the old object, but it is roughly speaking as
efficient as an inplace edit.
Returns : A new (fresh) Bio::PrimarySeqI object
Args : None
trunc
Title : trunc Usage : $subseq = $myseq->trunc(10,100); Function: Provides a truncation of a sequence. Returns : A fresh Bio::PrimarySeqI implementing object. Args : Two integers denoting first and last base of the sub-sequence.
translate
Title : translate
Usage : $protein_seq_obj = $dna_seq_obj->translate
Or if you expect a complete coding sequence (CDS) translation,
with initiator at the beginning and terminator at the end:
$protein_seq_obj = $cds_seq_obj->translate(-complete => 1);
Or if you want translate() to find the first initiation
codon and return the corresponding protein:
$protein_seq_obj = $cds_seq_obj->translate(-orf => 1);
Function: Provides the translation of the DNA sequence using full
IUPAC ambiguities in DNA/RNA and amino acid codes.
The complete CDS translation is identical to EMBL/TREMBL
database translation. Note that the trailing terminator
character is removed before returning the translated protein
object.
Note: if you set $dna_seq_obj->verbose(1) you will get a
warning if the first codon is not a valid initiator.
Returns : A Bio::PrimarySeqI implementing object
Args : -terminator
character for terminator, default '*'
-unknown
character for unknown, default 'X'
-frame
positive integer frame shift (in bases), default 0
-codontable_id
integer codon table id, default 1
-complete
boolean, if true, complete CDS is expected. default false
-complete_codons
boolean, if true, codons which are incomplete are translated if a
suitable amino acid is found. For instance, if the incomplete
codon is 'GG', the completed codon is 'GGN', which is glycine
(G). Defaults to 'false'; setting '-complete' also makes this
true.
-throw
boolean, throw exception if ORF not complete, default false
-orf
if 'longest', find longest ORF. other true value, find
first ORF. default 0
-codontable
optional L<Bio::Tools::CodonTable> object to use for
translation
-start
optional three-character string to force as initiation
codon (e.g. 'atg'). If unset, start codons are
determined by the CodonTable. Case insensitive.
-offset
optional positive integer offset for fuzzy locations.
if set, must be either 1, 2, or 3
Notes
The -start argument only applies when -orf is set to 1. By default all initiation codons found in the given codon table are used but when ``start'' is set to some codon this codon will be used exclusively as the initiation codon. Note that the default codon table (NCBI ``Standard'') has 3 initiation codons!
By default translate() translates termination codons to the some character (default is *), both internal and trailing codons. Setting ``-complete'' to 1 tells translate() to remove the trailing character.
-offset is used for seqfeatures which contain the the \codon_start tag and can be set to 1, 2, or 3. This is the offset by which the sequence translation starts relative to the first base of the feature
For details on codon tables used by translate() see Bio::Tools::CodonTable.
Deprecated argument set (v. 1.5.1 and prior versions) where each argument is an element in an array:
1: character for terminator (optional), defaults to '*'.
2: character for unknown amino acid (optional), defaults to 'X'.
3: frame (optional), valid values are 0, 1, 2, defaults to 0.
4: codon table id (optional), defaults to 1.
5: complete coding sequence expected, defaults to 0 (false).
6: boolean, throw exception if not complete coding sequence
(true), defaults to warning (false)
7: codontable, a custom Bio::Tools::CodonTable object (optional).
transcribe()
Title : transcribe
Usage : $xseq = $seq->transcribe
Function: Convert base T to base U
Returns : PrimarySeqI object of alphabet 'rna' or
undef if $seq->alphabet ne 'dna'
Args :
rev_transcribe()
Title : rev_transcribe
Usage : $rtseq = $seq->rev_transcribe
Function: Convert base U to base T
Returns : PrimarySeqI object of alphabet 'dna' or
undef if $seq->alphabet ne 'rna'
Args :
id
Title : id
Usage : $id = $seq->id()
Function: ID of the sequence. This should normally be (and actually is in
the implementation provided here) just a synonym for display_id().
Returns : A string.
Args :
length
Title : length Usage : $len = $seq->length() Function: Returns : Integer representing the length of the sequence. Args :
desc
Title : desc
Usage : $seq->desc($newval);
$description = $seq->desc();
Function: Get/set description text for a seq object
Returns : Value of desc
Args : newvalue (optional)
is_circular
Title : is_circular
Usage : if( $obj->is_circular) { # Do something }
Function: Returns true if the molecule is circular
Returns : Boolean value
Args : none
Private functions
These are some private functions for the PrimarySeqI interface. You do not need to implement these functions_find_orfs_nucleotide
Title : _find_orfs_nucleotide
Usage :
Function: Finds ORF starting at 1st initiation codon in nucleotide sequence.
The ORF is not required to have a termination codon.
Example :
Returns : a list of string coordinates of ORF locations (0-based half-open),
sorted descending by length (so that the longest is first)
as: [ start, end, frame, length ], [ start, end, frame, length ], ...
Args : Nucleotide sequence,
CodonTable object,
(optional) alternative initiation codon (e.g. 'ATA'),
(optional) boolean that, if true, stops after finding the
first available ORF
_attempt_to_load_Seq
Title : _attempt_to_load_Seq Usage : Function: Example : Returns : Args :