NAME

Bio::Grep::Backend::BackendI - Superclass for all back-ends

DESCRIPTION

Bio::Grep::Backend::BackendI is the superclass for all back-ends. Don't use this class directly.

METHODS

See Bio::Grep::Root for inherited methods.

CONSTRUCTOR

new(): This method constructs a Bio::Grep::Backend::BackendI object and is never used directly. Rather, all other back-ends in this package inherit the methods of this interface and call its constructor internally.

PACKAGE METHODS

$sbe->next_res

Returns next result as a Bio::Grep::SearchResult object after search() was called.

$sbe->search();

while ( my $res = $sbe->next_res ) {
    # output result
}

$sbe->settings()

Get the settings. This is a Bio::Grep::SearchSettings object

# search for the reverse complement and allow 4 mismatches
$sbe->settings->database('ATH1.cdna');
$sbe->settings->query('UGAACAGAAAGCUCAUGAGCC');
$sbe->settings->reverse_complement(1);
$sbe->settings->mismatches(4);

$sbe->features()

Get available features. This is a hash. Valid features are MISMATCHES, GUMISMATCHES, EDITDISTANCE, INSERTIONS, DELETIONS, FILTERS, NATIVE_ALIGNMENTS, PROTEINS, UPSTREAM, DOWNSTREAM, MAXHITS, COMPLETE, QUERY, QUERY_FILE, QUERY_LENGTH, DIRECT_AND_REV_COM, SHOWDESC, QSPEEDUP, HXDROP, EXDROP, EVALUE and PERCENT_IDENTITY.

if (defined($sbe->features->{GUMISMATCHES})) {
        # $sbe->settings->gumismatches(0);
        $sbe->settings->gumismatches(0.5);
} else {
      print "\nBack-end does not support wobble pairs\n";
}

$sbe->get_alphabet_of_database($db)

Returns 'dna' if the specified database is a DNA database, 'protein' otherwise.

ABSTRACT METHODS

Every back-end must implement these methods.

$sbe->search

This method starts the back-end with the settings specified in the Bio::Grep::SearchSettings object $sbe->settings.

$sbe->search();

This method also accepts an hash reference with settings. In this case, all previous defined options except all paths and the database are set to their default values.

$sbe->search({ mismatches => 2, 
               reverse_complement => 0, 
               query => $query });

$sbe->generate_database({ file => $file })

Creates a symlink to the specified file in the datapath directory ($sbe->settings->datapath) and generates a database. You have to do this only once for every file. Returns 1 if database generation was successful.

Optional arguments in the hash reference are:

format: The format of file. Default is Fasta. See the documentation of your back-end and Bio::SeqIO for supported formats. Only Fasta is thoroughly tested.
description: The description of the database. Later, you can access these descriptions with get_databases(). Default is the filename of file.
copy: Instead of adding a symlink to file in the data directory, copy the file. Useful for platforms that don't support symbolic links. Default 0 (create a symlink).
datapath: $sbe->settings->datapath is called with this value.
prefix_length: Vmatch option: prefix length for bucket sort. If not defined, then mkvtree automatically determines a reasonable prefix length.
verbose: Generate the database more verbosely. Default is 0.

Example:

$sbe->generate_database({
          file        => 'ATH1.cdna',
          format      => 'Fasta',
          description => 'AGI Transcripts',
          copy        => 1, 
          datapath    => 'data',
          verbose     => 1,
  });

$sbe->get_databases

Returns a hash with all available databases. The keys are the filenames, the values are descriptions (or the filename if no description is available).

my %local_dbs_description = $sbe->get_databases();
my @local_dbs = sort keys %local_dbs_description;

# take first available database 
$sbe->settings->database($local_dbs[0]);

$sbe->get_sequences

This method returns all sequences with the ids in the specified array reference as a Bio::SeqIO object.

  my $seqio = $sbe->get_sequences([$id]);
  my $string;  my $stringio = IO::String->new($string);
  my $out = Bio::SeqIO->new('-fh' => $stringio,
                            '-format' => 'fasta');

  while ( my $seq = $seqio->next_seq() ) {
     # write the sequences in a string
     $out->write_seq($seq);
  }
  print $string;

$sbe->available_sort_modes()

Returns a hash with the available result sort modes. Keys are the modes you can set with $sbe->settings->sort($mode), values a short description.

INTERNAL METHODS

Only back-ends should call them directly. These internal methods are documented for authors of new back-ends.

_check_search_settings

Performs some basic error checking. Important security checks, because we use system(). So we should check, if we get what we assume.

Because every back-end should call this method at the top of its search method, we clean things like old search results here up.

_prepare_query

Another important method that every back-end must call. Prepares the query, for example calculating the reverse complement if necessary, returns the prepared query. settings->query is unchanged!

_prepare_generate_database(@args)

The method generate_database() should call this internal method as first step. It checks if the first argument is a valid hash reference (see generate_database()), sets default values for undefined keys and returns this modifed argument hash. Creates a symlink of the specified file (or copies this file) in the data directory. Generates a .nfo file with the description of the database.

An implementation of generate_database should look like this:

sub generate_database {
    my ( $self, @args ) = @_;
    my %args = $self->_prepare_generate_database(@args);

    if (defined $args{skip}) {
        return 0;
    }   
    # create the back-end specific indices
    ... 
    
    $self->_create_index_and_alphabet_file( $args{filename} );
    return $args{filename};
}

_get_alignment( $seq_query, $seq_subject )

Calculates and returns an alignment of two Bio::Seq objects. Requires EMBOSS and bioperl-run.

_get_databases($suffix)

This method searches the data directory for files ending with $suffix and returns this list of files in an array.

Substitutes $suffix with .nfo from all found files and searches for an info file with that name. The content of that file will be used as description. When no file is found, the description will be the filename without the suffix:

%dbs = _get_databases('.al1'); # finds file ATH1.cdna.al1, searches 
                               # for ATH1.cdna.nfo
print $dbs{'ATH1.cdna'};       # prints content of ATH1.cdna.nfo
                               # or 'ATH1.cdna'

_get_sequences_from_bio_index($id)

GUUGle, RE and Agrep back-ends use Bio::Index for sequence id queries (implemented in this this method). Returns a Bio::SeqIO object.

_create_tmp_query_file()

Examines query, query_file and reverse_complement and generates a temporary Fasta file that is passed in the system() call to the back-end. If the environment variable BIOGREPDEBUG is not set, then this file will be deleted when the script exits.

_create_index_and_alphabet_file($fastafile)

Creates an index of the specified Fasta file with Bio::Index::Fasta. Creates an Vmatch alphabet file.

_parse_regions($hash_ref)

Takes as argument a hash reference with the gene sequence and the hit coordinates (keys complete_seq, subject_begin and subject_end, respectively). Calculates the upstream, subject and downstream sequence.

my ( $upstream_seq, $subject_seq, $downstream_seq ) =
    $self->_parse_regions({ 
        complete_seq => $complete_seq,
        subject_begin=> $subject_begin, 
        subject_end  => $subject_end, 
    });

DEPRECATED METHODS

$sbe->results()

DEPRECATED. Get the results after search() was called. This is an array of Bio::Grep::SearchResult objects.

$sbe->search();

foreach my $res (@{$sbe->results}) {
      # output result
}

Use next_res() instead.

$sbe->generate_database_out_of_fastafile($fastafile)

DEPRECATED. Use generate_database() instead.

DIAGNOSTICS

See Bio::Grep::Root for other diagnostics.

Alphabet of query and database not equal

You tried to search with DNA/RNA query in protein database or vice versa. Bio::Root::BadParameter.

Back-end does not support protein data

You tried to generate a protein database with a back-end that does not support protein data. Bio::Root::BadParameter.

Can't combine editdistance and mismatches.

Set either editdistance or mismatches, not both. Bio::Root::BadParameter

Can't copy ... to ...

It was not possible to copy the Fasta file in generate_database() in the data directory. Check path and permissions. Bio::Root::IOException.

Database not defined.

You forgot to define a database. You have to build a database with $sbe->generate_database (once) and set it with $sbe->settings->database. Example:

$sbe->generate_database('ATH1.cdna");
$sbe->settings->database('ATH1.cdna');

Bio::Root::BadParameter.

Database not found.

The specified database was not found. Check name and $sbe->settings->datapath. Bio::Root::BadParameter.

Database not valid (insecure characters).

The database name is not valid. Allowed characters are 'a-z', 'A-z','0-9', '.' , '-' and '_'. Bio::Root::BadParameter.

Invalid arguments. Hashref assumed.

The method generate_database() assumes as first argument a hash reference. Bio::Root::BadParameter.

No such file.

The file you have specified in generate_database() does not exist. Bio::Root::BadParameter.

Query and query_file are set. I am confused...

You specified a query and a query file. Bio::Root::BadParameter.

Query not defined.

You forgot to define a query or a query file. Bio::Root::BadParameter.

Reverse complement only available for DNA databases.

Either reverse_complement or direct_and_rev_com is set and the specified database is a protein database. These two feature are only available for DNA databases.

Sort mode not valid.

The specified sort mode ($sbe->settings->sort) is not valid. You can get all valid sort modes with $sbe->available_sort_modes() See Bio::Grep::Backend::Vmatch, Bio::Grep::Backend::GUUGle, Bio::Grep::Backend::RE and Bio::Grep::Backend::Agrep for details. Bio::Root::BadParameter.

FILES

Requires EMBOSS and Bio::Factory::EMBOSS for the Needleman-Wunsch local alignment implementation from EMBOSS. The internal method _get_alignment($seq_a, $seq_b) can then calculate an alignment for back-ends that do not generate an alignment (like Bio::Grep::Backend::Agrep).

AUTHOR

Markus Riester, <mriester@gmx.de>

LICENCE AND COPYRIGHT

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

To install Bio::Grep, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Bio::Grep

CPAN shell

perl -MCPAN -e shell
install Bio::Grep

For more information on module installation, please visit the detailed CPAN module installation guide.

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