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Bio::ASN1::Sequence::Indexer - Indexes NCBI Sequence files.


version 1.73


  use Bio::ASN1::Sequence::Indexer;

  # creating & using the index is just a few lines
  my $inx = Bio::ASN1::Sequence::Indexer->new(
    -filename => 'seq.idx',
    -write_flag => 'WRITE'); # needed for make_index call, but if opening
                             # existing index file, don't set write flag!
  $inx->make_index('seq1.asn', 'seq2.asn');
  my $seq = $inx->fetch('AF093062'); # Bio::Seq obj for Sequence (doesn't work yet)
  # alternatively, if one prefers just a data structure instead of objects
  $seq = $inx->fetch_hash('AF093062'); # a hash produced by Bio::ASN1::Sequence
                            # that contains all data in the Sequence record


Bio::ASN1::Sequence::Indexer is a Perl Indexer for NCBI Sequence genome databases. It processes an ASN.1-formatted Sequence record and stores the file position for each record in a way compliant with Bioperl standard (in fact its a subclass of Bioperl's index objects).

Note that this module does not parse record, because it needs to run fast and grab only the gene ids. For parsing record, use Bio::ASN1::Sequence.

As with Bio::ASN1::Sequence, this module is best thought of as beta version - it works, but is not fully tested.



  Parameters: $geneid - id for the Sequence record to be retrieved
  Example:    my $hash = $indexer->fetch(10); # get Sequence #10
  Function:   fetch the data for the given Sequence id.
  Returns:    A Bio::Seq object produced by Bio::SeqIO::sequence
  Notes:      Bio::SeqIO::sequence does not exist and probably won't
                exist for a while!  So call fetch_hash instead


  Parameters: $seqid - id for the Sequence record to be retrieved
  Example:    my $hash = $indexer->fetch_hash('AF093062');
  Function:   fetch a hash produced by Bio::ASN1::Sequence for given id
  Returns:    A data structure containing all data items from the Sequence
  Notes:      Alternative to fetch()







  Title   : _file_handle
  Usage   : $fh = $index->_file_handle( INT )
  Function: Returns an open filehandle for the file
            index INT.  On opening a new filehandle it
            caches it in the @{$index->_filehandle} array.
            If the requested filehandle is already open,
            it simply returns it from the array.
  Example : $fist_file_indexed = $index->_file_handle( 0 );
  Returns : ref to a filehandle
  Args    : INT
  Notes   : This function is copied from Bio::Index::Abstract. Once that module
              changes file handle code like I do below to fit perl 5.005_03, this
              sub would be removed from this module


Bio::ASN1::Sequence, Bioperl and all dependencies therein.


Same as Bio::ASN1::EntrezGene


Please check out perldoc for Bio::ASN1::EntrezGene for more info.


Liu, Mingyi, and Andrei Grigoriev. "Fast parsers for Entrez Gene." Bioinformatics 21, no. 14 (2005): 3189-3190.


Any OS that Perl & Bioperl run on.


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.              - General discussion    - About the mailing lists


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

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:


Dr. Mingyi Liu <>


This software is copyright (c) 2005 by Mingyi Liu, 2005 by GPC Biotech AG, and 2005 by Altana Research Institute.

This software is available under the same terms as the perl 5 programming language system itself.