IO documentation.

Bio::Structure IO

Included libraries

Package variables

General documentation

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Summary

Bio::Structure::IO - Handler for Structure Formats

Package variables

Privates (from "my" definitions)

$entry = 0

Included modules

Bio::PrimarySeq

Bio::Root::Root

Inherit

Bio::Root::IO Bio::Root::Root

Synopsis

    use Bio::Structure::IO;

    $in  = Bio::Structure::IO->new(-file => "inputfilename" , '-format' => 'pdb');
    $out = Bio::Structure::IO->new(-file => ">outputfilename" , '-format' => 'pdb');
    # note: we quote -format to keep older perl's from complaining.

    while ( my $struc = $in->next_structure() ) {
	$out->write_structure($struc);
    }

now, to actually get at the structure object, use the standard Bio::Structure
methods (look at Bio::Structure if you don't know what they are)

    use Bio::Structure::IO;

    $in  = Bio::Structure::IO->new(-file => "inputfilename" , '-format' => 'pdb');

    while ( my $struc = $in->next_structure() ) {
       print "Structure ",$struc->id," number of models: ",scalar $struc->model,"\n";
    }

Description

[ The following description is a copy-paste from the Bio::SeqIO description.
This is not surprising as the code is also mostly a copy. ]
Bio::Structure::IO is a handler module for the formats in the Structure::IO set
(eg, Bio::Structure::IO::pdb). It is the officially sanctioned way of getting at
the format objects, which most people should use.
The Bio::Structure::IO system can be thought of like biological file handles.
They are attached to filehandles with smart formatting rules (eg, PDB format)
and can either read or write structure objects (Bio::Structure objects, or
more correctly, Bio::Structure::StructureI implementing objects, of which
Bio::Structure is one such object). If you want to know what to do with a
Bio::Structure object, read Bio::Structure
The idea is that you request a stream object for a particular format.
All the stream objects have a notion of an internal file that is read
from or written to. A particular Structure::IO object instance is configured
for either input or output. A specific example of a stream object is
the Bio::Structure::IO::pdb object.
Each stream object has functions

   $stream->next_structure();

and

   $stream->write_structure($struc);

also

   $stream->type() # returns 'INPUT' or 'OUTPUT'

As an added bonus, you can recover a filehandle that is tied to the
Structure::IOIO object, allowing you to use the standard <> and print operations
to read and write structure::IOuence objects:

    use Bio::Structure::IO;

    $stream = Bio::Structure::IO->newFh(-format => 'pdb'); # read from standard input

    while ( $structure = <$stream> ) {
	# do something with $structure
    }

and

    print $stream $structure; # when stream is in output mode

Methods

DESTROY	No description	Code
PRINT	No description	Code
READLINE	No description	Code
TIEHANDLE	Description	Code
_concatenate_lines	Description	Code
_filehandle	Description	Code
_guess_format	Description	Code
_initialize	No description	Code
_load_format_module	Description	Code
fh	Description	Code
new	Description	Code
newFh	Description	Code
next_structure	Description	Code
write_seq	No description	Code

Methods description

TIEHANDLE(), READLINE(), PRINT()

These provide the tie interface. See perltie for more details.

_concatenate_lines

 Title   : _concatenate_lines
 Usage   : $s = _concatenate_lines($line, $continuation_line)
 Function: Private. Concatenates two strings assuming that the second stems
           from a continuation line of the first. Adds a space between both
           unless the first ends with a dash.

           Takes care of either arg being empty.
 Example :
 Returns : A string.
 Args    :

_filehandle

 Title   : _filehandle
 Usage   : $obj->_filehandle($newval)
 Function: This method is deprecated. Call _fh() instead.
 Example :
 Returns : value of _filehandle
 Args    : newvalue (optional)

_guess_format

 Title   : _guess_format
 Usage   : $obj->_guess_format($filename)
 Function:
 Example :
 Returns : guessed format of filename (lower case)
 Args    :

_load_format_module

 Title   : _load_format_module
 Usage   : *INTERNAL Structure::IO stuff*
 Function: Loads up (like use) a module at run time on demand
 Example :
 Returns :
 Args    :

fh

 Title   : fh
 Usage   : $obj->fh
 Function:
 Example : $fh = $obj->fh;      # make a tied filehandle
           $structure = <$fh>;   # read a structure object
           print $fh $structure; # write a structure object
 Returns : filehandle tied to the Bio::Structure::IO::Fh class
 Args    :

new

 Title   : new
 Usage   : $stream = Bio::Structure::IO->new(-file => $filename, -format => 'Format')
 Function: Returns a new structIOstream
 Returns : A Bio::Structure::IO handler initialised with the appropriate format
 Args    : -file => $filename
           -format => format
           -fh => filehandle to attach to

newFh

 Title   : newFh
 Usage   : $fh = Bio::Structure::IO->newFh(-file=>$filename,-format=>'Format')
 Function: does a new() followed by an fh()
 Example : $fh = Bio::Structure::IO->newFh(-file=>$filename,-format=>'Format')
           $structure = <$fh>;   # read a structure object
           print $fh $structure; # write a structure object
 Returns : filehandle tied to the Bio::Structure::IO::Fh class
 Args    :

next_structure

 Title   : next_structure
 Usage   : $structure = stream->next_structure
 Function: Reads the next structure object from the stream and returns it.

           Certain driver modules may encounter entries in the stream that
           are either misformatted or that use syntax not yet understood
           by the driver. If such an incident is recoverable, e.g., by
           dismissing a feature of a feature table or some other non-mandatory
           part of an entry, the driver will issue a warning. In the case
           of a non-recoverable situation an exception will be thrown.
           Do not assume that you can resume parsing the same stream after
           catching the exception. Note that you can always turn recoverable
           errors into exceptions by calling $stream->verbose(2) (see
           Bio::RootI POD page).
 Returns : a Bio::Structure structure object
 Args    : none

Methods code

DESTROY

description

prev

sub DESTROY {

    my $self = shift;

    $self->close();

}

PRINT

description

sub PRINT {

  my $self = shift;
  $self->{'structio'}->write_seq(@_);
}

1;

}

READLINE

description

sub READLINE {

  my $self = shift;
  return $self->{'structio'}->next_seq() unless wantarray;
  my (@list, $obj);
  push @list, $obj while $obj = $self->{'structio'}->next_seq();
  return @list;

}

TIEHANDLE

sub TIEHANDLE {

    my ($class,$val) = @_;
    return bless {'structio' => $val}, $class;

}

_concatenate_lines

sub _concatenate_lines {

    my ($self, $s1, $s2) = @_;
    $s1 .= " " if($s1 && ($s1 !~ /-$/) && $s2);
    return ($s1 ? $s1 : "") . ($s2 ? $s2 : "");

}

_filehandle

sub _filehandle {

    my ($self,@args) = @_;
    return $self->_fh(@args);

}

_guess_format

sub _guess_format {

   my $class = shift;
   return unless $_ = shift;
   return 'fasta'   if /\.(fasta|fast|seq|fa|fsa|nt|aa)$/i;
   return 'genbank' if /\.(gb|gbank|genbank)$/i;
   return 'scf'     if /\.scf$/i;
   return 'pir'     if /\.pir$/i;
   return 'embl'    if /\.(embl|ebl|emb|dat)$/i;
   return 'raw'     if /\.(txt)$/i;
   return 'gcg'     if /\.gcg$/i;
   return 'ace'     if /\.ace$/i;
   return 'bsml'    if /\.(bsm|bsml)$/i;
   return 'pdb'     if /\.(ent|pdb)$/i;

}

_initialize

description

sub _initialize {

    my($self, @args) = @_;
    
    # not really necessary unless we put more in RootI
    $self->SUPER::_initialize(@args);
    
    # initialize the IO part
    $self->_initialize_io(@args);

}

_load_format_module

sub _load_format_module {

  my ($format) = @_;
  my ($module, $load, $m);

  $module = "_<Bio/Structure/IO/$format.pm";
  $load = "Bio/Structure/IO/$format.pm";

  return 1 if $main::{$module};
  eval {
    require $load;
  };
  if ( $@ ) {
    print STDERR <<END;
$load: $format cannot be found
Exception $@
For more information about the Structure::IO system please see the 
Bio::Structure::IO docs.  This includes ways of checking for formats at 
compile time, not run time
END
  ;
    return;
  }
  return 1;

}

fh

sub fh {

  my $self = shift;
  my $class = ref($self) || $self;
  my $s = Symbol::gensym;
  tie $$s,$class,$self;
  return $s;
}


# _initialize is chained for all SeqIO classes

}

new

sub new {

    my ($caller,@args) = @_;
    my $class = ref($caller) || $caller;
    
    # or do we want to call SUPER on an object if $caller is an
    # object?
    if( $class =~ /Bio::Structure::IO::(\S+)/ ) {
	my ($self) = $class->SUPER::new(@args);	
	$self->_initialize(@args);
	return $self;
    } else { 

	my %param = @args;
	@param{ map { lc $_ } keys %param } = values %param; # lowercase keys
	my $format = $param{'-format'} || 
	    $class->_guess_format( $param{-file} || $ARGV[0] ) ||
		'pdb';
	$format = "\L$format";	# normalize capitalization to lower case

	# normalize capitalization
	return undef unless( &_load_format_module($format) );
	return "Bio::Structure::IO::$format"->new(@args);
    }

}

newFh

sub newFh {

  my $class = shift;
  return unless my $self = $class->new(@_);
  return $self->fh;

}

next_structure

sub next_structure {

   my ($self, $struc) = @_;
   $self->throw("Sorry, you cannot read from a generic Bio::Structure::IO object.");
}

# Do we want people to read out the sequence directly from a $structIO stream
# 
##=head2 next_primary_seq
##
## Title   : next_primary_seq
## Usage   : $seq = $stream->next_primary_seq
## Function: Provides a primaryseq type of sequence object
## Returns : A Bio::PrimarySeqI object
## Args    : none
##
##
##=cut
##
##sub next_primary_seq {
##   my ($self) = @_;
##
##   # in this case, we default to next_seq. This is because
##   # Bio::Seq's are Bio::PrimarySeqI objects. However we
##   # expect certain sub classes to override this method to provide
##   # less parsing heavy methods to retrieving the objects
##
##   return $self->next_seq();
##

}

write_seq

description

next

sub write_seq {

    my ($self, $struc) = @_;
    $self->throw("Sorry, you cannot write to a generic Bio::Structure::IO object.");
}


# De we need this here
#
##=head2 alphabet
##
## Title   : alphabet
## Usage   : $self->alphabet($newval)
## Function: Set/get the molecule type for the Seq objects to be created.
## Example : $seqio->alphabet('protein')
## Returns : value of alphabet: 'dna', 'rna', or 'protein'
## Args    : newvalue (optional)
## Throws  : Exception if the argument is not one of 'dna', 'rna', or 'protein'
##
##=cut
##
##sub alphabet {
##   my ($self, $value) = @_;
##
##   if ( defined $value) {
##       # instead of hard-coding the allowed values once more, we check by
##       # creating a dummy sequence object
##       eval {
##	   my $seq = Bio::PrimarySeq->new('-alphabet' => $value);
##       };
##       if($@) {
##	   $self->throw("Invalid alphabet: $value\n. See Bio::PrimarySeq for allowed values.");
##       }
##       $self->{'alphabet'} = "\L$value";
##   }
##   return $self->{'alphabet'};
##

}

General documentation

CONSTRUCTORS

Bio::Structure::IO->new()

   $stream = Bio::Structure::IO->new(-file => 'filename',   -format=>$format);
   $stream = Bio::Structure::IO->new(-fh   => \*FILEHANDLE, -format=>$format);
   $stream = Bio::Structure::IO->new(-format => $format);

The new() class method constructs a new Bio::Structure::IO object. The
returned object can be used to retrieve or print Bio::Structure objects.
new() accepts the following parameters:

-file

A file path to be opened for reading or writing. The usual Perl
conventions apply:

   'file'       # open file for reading
   '>file'      # open file for writing
   '>>file'     # open file for appending
   '+<file'     # open file read/write
   'command |'  # open a pipe from the command
   '| command'  # open a pipe to the command

-fh

You may provide new() with a previously-opened filehandle. For
example, to read from STDIN:

   $strucIO = Bio::Structure::IO->new(-fh => \*STDIN);

    Note that you must pass filehandles as references to globs.
    If neither a filehandle nor a filename is specified, then the module
will read from the @ARGV array or STDIN, using the familiar <>
semantics.
    A string filehandle is handy if you want to modify the output in the
memory, before printing it out. The following program reads in EMBL
formatted entries from a file and prints them out in fasta format with
some HTML tags:
[ not relevant for Bio::Structure::IO as only one format is supported
at the moment ]

  use Bio::SeqIO;
  use IO::String;
  my $in  = Bio::SeqIO->new('-file' => "emblfile" , 
  			    '-format' => 'EMBL');
  while ( my $seq = $in->next_seq() ) {
      # the output handle is reset for every file
      my $stringio = IO::String->new($string);
      my $out = Bio::SeqIO->new('-fh' => $stringio,
  			        '-format' => 'fasta');
      # output goes into $string
      $out->write_seq($seq);
      # modify $string
      $string =~ s|(>)(\w+)|$1<font color="Red">$2</font>|g;
      # print into STDOUT
      print $string;
  }

-format

Specify the format of the file. Supported formats include:

   PDB         Protein Data Bank format

If no format is specified and a filename is given, then the module
will attempt to deduce it from the filename. If this is unsuccessful,
PDB format is assumed.
The format name is case insensitive. 'PDB', 'Pdb' and 'pdb' are
all supported.

Bio::Structure::IO->newFh()

   $fh = Bio::Structure::IO->newFh(-fh   => \*FILEHANDLE, -format=>$format);
   $fh = Bio::Structure::IO->newFh(-format => $format);
   # etc.

This constructor behaves like new(), but returns a tied filehandle
rather than a Bio::Structure::IO object. You can read structures from this
object using the familiar <> operator, and write to it using
print(). The usual array and $_ semantics work. For example, you can
read all structure objects into an array like this:

  @structures = <$fh>;

Other operations, such as read(), sysread(), write(), close(), and printf()
are not supported.

OBJECT METHODS

See below for more detailed summaries. The main methods are:

$structure = $structIO->next_structure()

Fetch the next structure from the stream.

$structIO->write_structure($struc [,$another_struc,...])

Write the specified structure(s) to the stream.

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 one of the Bioperl mailing lists.
Your participation is much appreciated.

  bioperl-l@bioperl.org                  - General discussion
  http://bioperl.org/MailList.shtml      - About the mailing lists

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 email or the web:

  bioperl-bugs@bioperl.org
  http://bugzilla.bioperl.org/

AUTHOR - Ewan Birney, Lincoln Stein, Kris Boulez

Email birney@ebi.ac.uk, kris.boulez@algonomics
Describe contact details here

APPENDIX

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

write_structure

 Title   : write_structure
 Usage   : $stream->write_structure($structure)
 Function: writes the $structure object into the stream
 Returns : 1 for success and 0 for error
 Args    : Bio::Structure object