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Bio::SeqIO::chadoxml(3pm) User Contributed Perl Documentation Bio::SeqIO::chadoxml(3pm)


Bio::SeqIO::chadoxml - chadoxml sequence output stream


It is probably best not to use this object directly, but rather go through the SeqIO handler system:

    $writer = Bio::SeqIO->new(-file => ">chado.xml",
                              -format => 'chadoxml');
    # assume you already have Sequence or SeqFeature objects
    #after writing all seqs


This object can transform Bio::Seq objects to chadoxml flat file databases (for chadoxml DTD, see

This is currently a write-only module.

    $seqio = Bio::SeqIO->new(-file => '>outfile.xml',
                             -format => 'chadoxml'
                             -suppress_residues => 1,
                             -allow_residues => 'chromosome',
    # we have a Bio::Seq object $seq which is a gene located on
    # chromosome arm 'X', to be written out to chadoxml
    # before converting to chadoxml, $seq object B<must> be transformed
    # so that all the coordinates in $seq are against the source
    # feature to be passed into Bio::SeqIO::chadoxml->write_seq()
    # -- chromosome arm X in the example below.
                      -genus   => 'Homo',
                      -species => 'sapiens',

The chadoxml output of Bio::SeqIO::chadoxml->write_seq() method can be passed to the loader utility in XORT package ( to be loaded into chado.

This object is currently implemented to work with sequence and annotation data from whole genome projects deposited in GenBank. It may not be able to handle all different types of data from all different sources.

In converting a Bio::Seq object into chadoxml, a top-level feature is created to represent the object and all sequence features inside the Bio::Seq object are treated as subfeatures of the top-level feature. The Bio::SeqIO::chadoxml object calls Bio::SeqFeature::Tools::Unflattener to unflatten the flat feature list contained in the subject Bio::Seq object, to build gene model containment hierarchy conforming to chado central dogma model: gene --> mRNA --> exons and protein.

Destination of data in the subject Bio::Seq object $seq is as following:

    *$seq->display_id:  name of the top-level feature;
    *$seq->accession_number: if defined, uniquename and
                 feature_dbxref of the top-level
                 feature if not defined,
                 $seq->display_id is used as the
                 uniquename of the top-level feature;
    *$seq->molecule: transformed to SO type, used as the feature
            type of the top-level feature if -seq_so_type
            argument is supplied, use the supplied SO type
            as the feature type of the top-level feature;
    *$seq->species: organism of the top-level feature;
    *$seq->seq: residues of the top-level feature;
    *$seq->is_circular, $seq->division: feature_cvterm;
    *$seq->keywords, $seq->desc, comments: featureprop;
    *references: pub and feature_pub;
        medline/pubmed ids: pub_dbxref;
        comments: pubprop;
    *feature "source" span: featureloc for top-level feature;
    *feature "source" db_xref: feature_dbxref for top-level feature;
    *feature "source" other tags: featureprop for top-level feature;
    *subfeature 'symbol' or 'label' tag: feature uniquename, if
                     none of these is present, the chadoxml object
                     generates feature uniquenames as:
                     (e.g. foo-mRNA--1000..3000);
    *gene model: feature_relationship built based on the
                     containment hierarchy;
    *feature span: featureloc;
    *feature accession numbers: feature_dbxref;
    *feature tags (except db_xref, symbol and gene): featureprop;

Things to watch out for:

    *chado schema change: this version works with the chado
                               version tagged chado_1_01 in GMOD CVS.
    *feature uniquenames: especially important if using XORT
                              loader to do incremental load into
                              chado. may need pre-processing of the
                              source data to put the correct
                              uniquenames in place.
    *pub uniquenames: chadoxml->write_seq() has the FlyBase policy
                          on pub uniquenames hard-coded, it assigns
                          pub uniquenames in the following way: for
                          journals and books, use ISBN number; for
                          published papers, use MEDLINE ID; for
                          everything else, use FlyBase unique
                          identifier FBrf#. need to modify the code to
                          implement your policy. look for the comments
                          in the code.
    *for pubs possibly existing in chado but with no knowledge of
         its uniquename:put "op" as "match", then need to run the
                        output chadoxml through a special filter that
                        talks to chado database and tries to find the
                        pub by matching with the provided information
                        instead of looking up by the unique key. after
                        matching, the filter also resets the "match"
                        operation to either "force" (default), or
                        "lookup", or "insert", or "update". the
                        "match" operation is for a special FlyBase use
                        case. please modify to work according to your
    *chado initialization for loading:
        cv & cvterm: in the output chadoxml, all cv's and
                             cvterm's are lookup only. Therefore,
                             before using XORT loader to load the
                             output into chado, chado must be
                             pre-loaded with all necessary CVs and
                             CVterms, including "SO" , "property
                             type", "relationship type", "pub type",
                             "pubprop type", "pub relationship type",
                             "sequence topology", "GenBank feature
                             qualifier", "GenBank division". A pub by
                             the uniquename 'nullpub' of type 'null
                             pub' needs to be inserted.


Mailing Lists

User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to one of the Bioperl mailing lists. 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 the bugs and their resolution. Bug reports can be submitted via the web:

AUTHOR - Peili Zhang



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


 Title   : write_seq
 Usage   : $stream->write_seq(-seq=>$seq, -seq_so_type=>$seqSOtype,
                  -nounflatten=>0 or 1,
                  -is_analysis=>'true' or 'false',
 Function: writes the $seq object (must be seq) into chadoxml.
 Returns : 1 for success and 0 for error
 Args     : A Bio::Seq object $seq, optional $seqSOtype, $srcfeature,
            $srcfeattype, $nounflatten, $is_analysis and $data_source.

When $srcfeature (a string, the uniquename of the source feature) is given, the location and strand information of the top-level feature against the source feature will be derived from the sequence feature called 'source' of the $seq object, a featureloc record is generated for the top -level feature on $srcfeature. when $srcfeature is given, $srcfeattype must also be present. All feature coordinates in $seq should be against $srcfeature. $seqSOtype is the optional SO term to use as the type of the top-level feature. For example, a GenBank data file for a Drosophila melanogaster genome scaffold has the molecule type of "DNA", when converting to chadoxml, a $seqSOtype argument of "golden_path_region" can be supplied to save the scaffold as a feature of type "golden_path_region" in chadoxml, instead of "DNA". a feature with primary tag of 'source' must be present in the sequence feature list of $seq, to describe the whole sequence record.

In the current implementation:

  • non-mRNA records

    A top-level feature of type $seq->alphabet is generated for the whole GenBank record, features listed are unflattened for DNA records to build gene model feature graph, and for the other types of records all features in $seq are treated as subfeatures of the top-level feature.

  • mRNA records

    If a 'gene' feature is present, it must have a /symbol or /label tag to contain the uniquename of the gene. a top-level feature of type 'gene' is generated. the mRNA is written as a subfeature of the top-level gene feature, and the other sequence features listed in $seq are treated as subfeatures of the mRNA feature.


 Title    : suppress_residues
 Usage    : $obj->suppress_residues()        #get existing value
            $obj->suppress_residues($newval) #set new value
 Function : Keep track of the flag to suppress printing of residues in the
            chadoxml file. The default it to allow all residues to go into the
 Returns  : value of suppress_residues (a scalar)
 Args     : new value of suppress_residues (to set)


 Title    : allow_residues
 Usage    : $obj->allow_residues()        #get existing value
            $obj->allow_residues($feature_type) #set new value
 Function : Track the allow_residues type.  This can be used in conjunction
            with the suppress_residues flag to only allow residues from a
            specific feature type to be printed in the xml file, for example,
            only printing chromosome residues. When suppress_residues is set to
            true, then only chromosome features would would go into the xml
            file. If suppress_residues is not set, this function has no effect
            (since the default is to put all residues in the xml file).
 Returns  : value of allow_residues (string that corresponds to a feature type)
 Args     : new value of allow_residues (to set)
 Status   :


 Title    : return_ftype_hash
 Usage    : $obj->return_ftype_hash()
 Function : A simple hash where returning it has be factored out of the main
            code to allow subclasses to override it.
 Returns  : A hash that indicates what the name of the SO term is and what
            the name of the Sequence Ontology is in the cv table.
 Args     : The string that represents the SO term.
 Status   :


 Title    : return_reltypename
 Usage    : $obj->return_reltypename
 Function : Return the appropriate relationship type name depending on the
            feature type (typically part_of, but derives_from for polypeptide).
 Returns  : A relationship type name.
 Args     : A SO type name.
 Status   :


 Title    : next_seq
 Usage    : $obj->next_seq
 Function :
 Returns  :
 Args     :
 Status   : Not implemented (write only adaptor)


 Title    : _create_writer
 Usage    : $obj->_create_writer
 Function : Creates XML::Writer object and writes start tag
 Returns  : Nothing, though the writer persists as part of the chadoxml object
 Args     : None
 Status   :


 Title    : close_chadoxml
 Usage    : $obj->close_chadoxml
 Function : Writes the closing xml tag
 Returns  : None
 Args     : None
 Status   :


 Title    : handle_unreserved_tags
 Usage    : $obj->handle_unreserved_tags
 Function : Converts tag value pairs to xml-ready hashrefs
 Returns  : The array containing the hashrefs
 Args     : In order: the Seq or SeqFeature object, the key, and the hasharray
 Status   :


 Title    : handle_Alias_tag
 Usage    : $obj->handle_Alias_tag
 Function : Convert Alias values to synonym hash refs
 Returns  : An array of synonym hash tags
 Args     : The seq or seqFeature object and the synonym hash array
 Status   :


 Title    : handle_Ontology_tag
 Usage    : $obj->handle_Ontology_tag
 Function : Convert Ontology_term values to ontology term hash refs
 Returns  : An array of ontology term hash refs
 Args     : The seq or seqFeature object and the ontology term array
 Status   :


 Title    : handle_dbxref
 Usage    : $obj->handle_dbxref
 Function : Convert Dbxref values to dbxref hashref
 Returns  : An array of dbxref hashrefs
 Args     : A seq or seqFeature object and the dbxref array
 Status   :


 Title    : handle_source
 Usage    : $obj->handle_source
 Function :
 Returns  :
 Args     :
 Status   :


 Title    : _srcf_hash
 Usage    : $obj->_srcf_hash
 Function : Creates the srcfeature hash for use in featureloc hashes
 Returns  : The srcfeature hash
 Args     : The srcfeature name, the srcfeature type and a reference to the
            organism hash.
 Status   :
2018-10-27 perl v5.26.2