/ 
bioperl-1.5.2_005-RCb
/ Bio::SearchIO::blastxml

NAME

Bio::SearchIO::blastxml - A SearchIO implementation of NCBI Blast XML parsing.

SYNOPSIS

    use Bio::SearchIO;
    my $searchin = new Bio::SearchIO(-format => 'blastxml',
				     -file   => 't/data/plague_yeast.bls.xml');
    while( my $result = $searchin->next_result ) {
    }

    # one can also request that the parser NOT keep the XML data in memory
    # by using the tempfile initialization flag.
    my $searchin = new Bio::SearchIO(-tempfile => 1,
				     -format => 'blastxml',
				     -file   => 't/data/plague_yeast.bls.xml');
    while( my $result = $searchin->next_result ) {
    }

DESCRIPTION

This object implements a NCBI Blast XML parser. It requires XML::SAX; it is also recommended (for faster parsing) that XML::SAX::ExpatXS be installed and set as the default parser in ParserDetails.ini. This file is located in the SAX subdirectory of XML in your local perl library (normally in the 'site' directory). Currently, XML::SAX::Expat will NOT work as expected if set as default; you must have local copies of the NCBI DTDs if using XML::SAX::Expat.

There is one additional initialization flag from the SearchIO defaults - that is the -tempfile flag. If specified as true, then the parser will write out each report to a temporary filehandle rather than holding the entire report as a string in memory. The reason this is done in the first place is NCBI reports have an uncessary <?xml version="1.0"?> at the beginning of each report and RPS-BLAST reports have an additional unecessary RPS-BLAST tag at the top of each report. So we currently have implemented the work around by preparsing the file (yes it makes the process slower, but it works).

DEPENDENCIES

In addition to parts of the Bio:: hierarchy, this module uses:

XML::SAX

It is also recommended that XML::SAX::ExpatXS be installed and made the default XML::SAX parser using , along with the Expat library () for faster parsing. XML::SAX::Expat is not recommended; XML::SAX::ExpatXS is considered the current replacement for XML::SAX:Expat and is actively being considered to replace XML::SAX::Expat. XML::SAX::Expat will work, but only if you have local copies of the NCBI BLAST DTDs. This is due to issues with NCBI's BLAST XML format. The DTDs and the web address to obtain them are:

NCBI_BlastOutput.dtd	    
NCBI_BlastOutput.mod.dtd

http://www.ncbi.nlm.nih.gov/data_specs/dtd/

FEEDBACK

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

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:

http://bugzilla.open-bio.org/

AUTHOR - Jason Stajich

Email jason-at-bioperl.org

APPENDIX

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

new

 Title   : new
 Usage   : my $searchio = new Bio::SearchIO(-format => 'blastxml',
					    -file   => 'filename',
					    -tempfile => 1);
 Function: Initializes the object - this is chained through new in SearchIO
 Returns : Bio::SearchIO::blastxml object
 Args    : One additional argument from the format and file/fh parameters.
           -tempfile => boolean.  Defaults to false.  Write out XML data
                                  to a temporary filehandle to send to 
                                  PerlSAX parser.

_initialize

Title   : _initialize
Usage   : private
Function: Initializes the object - this is chained through new in SearchIO

next_result

Title   : next_result
Usage   : my $hit = $searchio->next_result;
Function: Returns the next Result from a search
Returns : Bio::Search::Result::ResultI object
Args    : none

SAX methods

start_document

Title   : start_document
Usage   : $parser->start_document;
Function: SAX method to indicate starting to parse a new document
Returns : none
Args    : none

end_document

Title   : end_document
Usage   : $parser->end_document;
Function: SAX method to indicate finishing parsing a new document
Returns : Bio::Search::Result::ResultI object
Args    : none

start_element

Title   : start_element
Usage   : $parser->start_element($data)
Function: SAX method to indicate starting a new element
Returns : none
Args    : hash ref for data

end_element

Title   : end_element
Usage   : $parser->end_element($data)
Function: Signals finishing an element
Returns : Bio::Search object dpending on what type of element
Args    : hash ref for data

characters

Title   : characters
Usage   : $parser->characters($data)
Function: Signals new characters to be processed
Returns : characters read
Args    : hash ref with the key 'Data'

use_tempfile

Title   : use_tempfile
Usage   : $obj->use_tempfile($newval)
Function: Get/Set boolean flag on whether or not use a tempfile
Example : 
Returns : value of use_tempfile
Args    : newvalue (optional)