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11 PAUSE users
14 non-PAUSE users.

Christopher Fields
and 1 contributors


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


    use Bio::SearchIO;
    my $searchin = Bio::SearchIO->new(-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 = Bio::SearchIO->new(-tempfile => 1,
                                     -format => 'blastxml',
                                     -file   => 't/data/plague_yeast.bls.xml');
    while( my $result = $searchin->next_result ) {


This object implements a NCBI Blast XML parser. It requires XML::SAX; it is also recommended (for faster parsing) that XML::SAX::ExpatXS or XML::LibXML be installed. Either 'XML::SAX::ExpatXS' or 'XML::LibXML::SAX::Parser' should be 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 and will not be supported.

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).


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


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:




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
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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:


AUTHOR - Jason Stajich

Email jason-at-bioperl.org


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


 Title   : new
 Usage   : my $searchio = Bio::SearchIO->new(-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.


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


 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


 Title   : result_count
 Usage   : $num = $stream->result_count;
 Function: Gets the number of Blast results that have been successfully parsed
           at the point of the method call.  This is not the total # of results
           in the file.
 Returns : integer
 Args    : none
 Throws  : none


 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)


 Title   : blasttype
 Usage   : $obj->blasttype($newtype)
 Function: Get/Set BLAST report type.
 Returns : BLAST report type
 Args    : case-insensitive string of types BLAST or PSIBLAST (default: BLAST)
 Note    : this is used to determine how reports are 'chunked' (in cases
           where multiple queries are submitted) and which XML handler
           to use when parsing the report(s)