# BioPerl module for Bio::DB::Taxonomy::greengenes
# Please direct questions and support issues to <bioperl-l@bioperl.org> 
# Cared for by Florent Angly <florent.angly@gmail.com>
# Copyright Florent Angly
# You may distribute this module under the same terms as perl itself

# POD documentation - main docs before the code

=head1 NAME

Bio::DB::Taxonomy::greengenes - Use the Greengenes taxonomy


  use Bio::DB::Taxonomy;

  my $db = Bio::DB::Taxonomy->new(
     -source   => 'greengenes',
     -taxofile => 'taxonomy_16S_candiv_gg_2011_1.txt'


I<This module is in beta. Its interface or its results may change in a future update.>

Bio::DB::Taxonomy::greengenes is an implementation of Bio::DB::Taxonomy which
stores and accesses the Greengenes taxonomy of Bacteria and Archaea. Internally,
it keeps the taxonomy into memory by using Bio::DB::Taxonomy::list. As a
consequence, note that the IDs assigned to the taxonomy nodes, e.g. gg123, are
arbitrary, contrary to the pre-defined IDs that NCBI assigns to taxons.

The latest release of the Greengene taxonomy (2011) contains about 4,600 taxa
and occupies about 4MB of memory once parsed into a Bio::DB::Taxonomy::greengenes
object. The taxonomy files taxonomy_16S_all_gg_2011_1.txt and
taxonomy_16S_candiv_gg_2011_1.txt that this module can use are available from


=head2 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.

  bioperl-l@bioperl.org                  - General discussion
  http://bioperl.org/wiki/Mailing_lists  - About the mailing lists

=head2 Support 

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.

=head2 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:


=head1 AUTHOR - Florent Angly



The rest of the documentation details each of the object methods.
Internal methods are usually preceded with a _


# Let the code begin...

package Bio::DB::Taxonomy::greengenes;
$Bio::DB::Taxonomy::greengenes::VERSION = '1.7.7';
use strict;
use base qw(Bio::DB::Taxonomy Bio::DB::Taxonomy::list);

$Bio::DB::Taxonomy::list::prefix = 'gg';

=head2 new

 Title   : new
 Usage   : my $obj = Bio::DB::Taxonomy::greengenes->new();
 Function: Builds a new Bio::DB::Taxonomy::greengenes object 
 Returns : an instance of Bio::DB::Taxonomy::greengenes
 Args    : -taxofile  => name of the file containing the taxonomic information,
                         typically 'taxonomy_16S_candiv_gg_2011_1.txt' (mandatory)


sub new {
   # Override Bio::DB::Taxonomy
   my($class, @args) = @_;
   my $self = $class->SUPER::new(@args);
   my ($taxofile) = $self->_rearrange([qw(TAXOFILE)], @args);
   if ( $taxofile ) {
      $self = $self->_build_taxonomy($taxofile);

   return $self;

sub _build_taxonomy {
   my ($self, $taxofile) = @_;

   my $all_ranks = ['kingdom', 'phylum', 'class', 'order', 'family', 'genus', 'species'];

   my $taxonomy = Bio::DB::Taxonomy::list->new();

   open my $fh, '<', $taxofile or $self->throw("Could not read file '$taxofile': $!");

   # Will skip header line: prokMSA_id	taxonomy
   my $prev_taxo_string = 'taxonomy'; 

   my $line;

   # Parse taxonomy lines. Example:
   # 348902	k__Bacteria; p__Bacteroidetes; c__Bacteroidia; o__Bacteroidales; f__Bacteroidaceae; g__Bacteroides; s__Bacteroides plebeius
   while ($line = <$fh>) {
      chomp $line;
      my ($prokmsa_id, $taxo_string) = split "\t", $line;

      # Skip taxonomy string already seen on previous line (much faster!)
      next if $taxo_string eq $prev_taxo_string;
      $prev_taxo_string = $taxo_string;

      # Remove ambiguous taxons, i.e. go from:
      #    k__Archaea; p__pMC2A384; c__; o__; f__; g__; s__
      # to:
      #    k__Archaea; p__pMC2A384
      my $names = [split /;\s*/, $taxo_string];
      while ( ($names->[-1] || '') =~ m/__$/) {
         pop @$names;

      my $nof_ranks = scalar @$names;
      next if $nof_ranks < 1;

         -ranks => [ @{$all_ranks}[0..$nof_ranks-1] ],
         -names => $names,


   close $fh;

   return $taxonomy;