Ewan Birney


Bio::PrimarySeqI - Interface definition for a Bio::PrimarySeq


    # get a Bio::PrimarySeqI compliant object somehow

    # to test 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


This object defines an abstract interface to basic sequence information. 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 consideres 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 inheriet 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.


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AUTHOR - Ewan Birney

Email birney@sanger.ac.uk


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.


 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


 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, ie 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


 Title   : display_id
 Usage   : $id_string = $obj->display_id();
 Function: returns the display id, aka 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/convience issues
 Returns : A string
 Args    : None
 Status  : Virtual


 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
 Returns : A string
 Args    : None
 Status  : Virtual


 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


 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',
 Example :
 Returns : 1 or 0
 Args    :


 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 type - if there is no type specified it
           has to guess.
 Args    : none
 Status  : Virtual

Optional Implementation 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.

All of revcom(), trunc(), and translate() 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


 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


 Title   : trunc
 Usage   : $subseq = $myseq->trunc(10,100);
 Function: Provides a truncation of a sequence,

 Example :
 Returns : a fresh Bio::PrimarySeqI implementing object
 Args    : Two integers denoting first and last base of the sub-sequence.


 Title   : translate
 Usage   : $protein_seq_obj = $dna_seq_obj->translate
           #if full CDS expected:
           $protein_seq_obj = $cds_seq_obj->translate(undef,undef,undef,undef,1);

           Provides the translation of the DNA sequence using full
           IUPAC ambiguities in DNA/RNA and amino acid codes.

           The full CDS translation is identical to EMBL/TREMBL
           database translation. Note that the trailing terminator
           character is removed before returning the translation

           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    : character for terminator (optional) defaults to '*'
           character for unknown amino acid (optional) defaults to 'X'
           frame (optional) valid values 0, 1, 2, defaults to 0
           codon table id (optional) defaults to 1
           complete coding sequence expected, defaults to 0 (false)
           boolean, throw exception if not complete CDS (true) or defaults to warning (false)


 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().
 Example :
 Returns : A string.
 Args    :


 Title   : length
 Usage   : $len = $seq->length()
 Example :
 Returns : integer representing the length of the sequence.
 Args    :


 Title   : desc
 Usage   : $seq->desc($newval);
           $description = $seq->desc();
 Function: Get/set description text for a seq object
 Example :
 Returns : value of desc
 Args    : newvalue (optional)


 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


 Title   : _attempt_to_load_Seq
 Usage   :
 Example :
 Returns :
 Args    :