| Bio::SeqIO(3pm) | User Contributed Perl Documentation | Bio::SeqIO(3pm) |
Bio::SeqIO - Handler for SeqIO Formats
use Bio::SeqIO;
$in = Bio::SeqIO->new(-file => "inputfilename" ,
-format => 'Fasta');
$out = Bio::SeqIO->new(-file => ">outputfilename" ,
-format => 'EMBL');
while ( my $seq = $in->next_seq() ) {
$out->write_seq($seq);
}
# Now, to actually get at the sequence object, use the standard Bio::Seq
# methods (look at Bio::Seq if you don't know what they are)
use Bio::SeqIO;
$in = Bio::SeqIO->new(-file => "inputfilename" ,
-format => 'genbank');
while ( my $seq = $in->next_seq() ) {
print "Sequence ",$seq->id, " first 10 bases ",
$seq->subseq(1,10), "\n";
}
# The SeqIO system does have a filehandle binding. Most people find this
# a little confusing, but it does mean you can write the world's
# smallest reformatter
use Bio::SeqIO;
$in = Bio::SeqIO->newFh(-file => "inputfilename" ,
-format => 'Fasta');
$out = Bio::SeqIO->newFh(-format => 'EMBL');
# World's shortest Fasta<->EMBL format converter:
print $out $_ while <$in>;
Bio::SeqIO is a handler module for the formats in the SeqIO set (eg, Bio::SeqIO::fasta). It is the officially sanctioned way of getting at the format objects, which most people should use.
The Bio::SeqIO system can be thought of like biological file handles. They are attached to filehandles with smart formatting rules (eg, genbank format, or EMBL format, or binary trace file format) and can either read or write sequence objects (Bio::Seq objects, or more correctly, Bio::SeqI implementing objects, of which Bio::Seq is one such object). If you want to know what to do with a Bio::Seq object, read Bio::Seq.
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 SeqIO object instance is configured for either input or output. A specific example of a stream object is the Bio::SeqIO::fasta object.
Each stream object has functions
$stream->next_seq();
and
$stream->write_seq($seq);
As an added bonus, you can recover a filehandle that is tied to the SeqIO object, allowing you to use the standard <> and print operations to read and write sequence objects:
use Bio::SeqIO;
$stream = Bio::SeqIO->newFh(-format => 'Fasta',
-fh => \*ARGV);
# read from standard input or the input filenames
while ( $seq = <$stream> ) {
# do something with $seq
}
and
print $stream $seq; # when stream is in output mode
This makes the simplest ever reformatter
#!/usr/bin/perl
use strict;
my $format1 = shift;
my $format2 = shift || die
"Usage: reformat format1 format2 < input > output";
use Bio::SeqIO;
my $in = Bio::SeqIO->newFh(-format => $format1, -fh => \*ARGV );
my $out = Bio::SeqIO->newFh(-format => $format2 );
# Note: you might want to quote -format to keep older
# perl's from complaining.
print $out $_ while <$in>;
$seqIO = Bio::SeqIO->new(-file => 'seqs.fasta', -format => $format); $seqIO = Bio::SeqIO->new(-fh => \*FILEHANDLE, -format => $format); $seqIO = Bio::SeqIO->new(-string => $string , -format => $format); $seqIO = Bio::SeqIO->new(-format => $format);
The new() class method constructs a new Bio::SeqIO object. The returned object can be used to retrieve or print Seq objects. new() accepts the following parameters:
'file' # open file for reading
'>file' # open file for writing
'>>file' # open file for appending
'+<file' # open file read/write
To read from or write to a piped command, open a filehandle and use the -fh option.
my $seqIO = Bio::SeqIO->new(-fh => \*STDIN);
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:
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;
}
Filehandles can also be used to read from or write to a piped command:
use Bio::SeqIO;
#convert .fastq.gz to .fasta
open my $zcat, 'zcat seq.fastq.gz |' or die $!;
my $in=Bio::SeqIO->new(-fh=>$zcat,
-format=>'fastq');
my $out=Bio::SeqIO->new(-file=>'>seq.fasta',
-format=>'fasta');
while (my $seq=$in->next_seq) {
$out->write_seq($seq)
}
my $string = ">seq1\nACGCTAGCTAGC\n";
my $seqIO = Bio::SeqIO->new(-string => $string);
If no format is specified and a filename is given then the module will attempt to deduce the format from the filename suffix. If there is no suffix that Bioperl understands then it will attempt to guess the format based on file content. If this is unsuccessful then SeqIO will throw a fatal error.
The format name is case-insensitive: 'FASTA', 'Fasta' and 'fasta' are all valid.
my $gb = Bio::SeqIO->new(-file => "<gball.gbk",
-format => "gb");
my $fa = Bio::SeqIO->new(-file => ">gball.fa",
-format => "fasta",
-flush => 0); # go as fast as we can!
while($seq = $gb->next_seq) { $fa->write_seq($seq) }
$fh = Bio::SeqIO->newFh(-fh => \*FILEHANDLE, -format=>$format); $fh = Bio::SeqIO->newFh(-format => $format); # etc.
This constructor behaves like new(), but returns a tied filehandle rather than a Bio::SeqIO object. You can read sequences from this object using the familiar <> operator, and write to it using print(). The usual array and $_ semantics work. For example, you can read all sequence objects into an array like this:
@sequences = <$fh>;
Other operations, such as read(), sysread(), write(), close(), and printf() are not supported.
See below for more detailed summaries. The main methods are:
Fetch the next sequence from the stream, or nothing if no more.
Write the specified sequence(s) to the stream.
These provide the tie interface. See perltie for more details.
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/wiki/Mailing_lists - About the mailing lists
Please direct usage questions or support issues to the mailing list:
bioperl-l@bioperl.org
rather than to the module maintainer directly. Many experienced and responsive 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.
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:
https://github.com/bioperl/bioperl-live/issues
Email birney@ebi.ac.uk
lstein@cshl.org
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _
Title : new
Usage : $stream = Bio::SeqIO->new(-file => 'sequences.fasta',
-format => 'fasta');
Function: Returns a new sequence stream
Returns : A Bio::SeqIO stream initialised with the appropriate format
Args : Named parameters indicating where to read the sequences from or to
write them to:
-file => filename, OR
-fh => filehandle to attach to, OR
-string => string
Additional arguments, all with reasonable defaults:
-format => format of the sequences, usually auto-detected
-alphabet => 'dna', 'rna', or 'protein'
-flush => 0 or 1 (default: flush filehandles after each write)
-seqfactory => sequence factory
-locfactory => location factory
-objbuilder => object builder
See Bio::SeqIO::Handler
Title : newFh
Usage : $fh = Bio::SeqIO->newFh(-file=>$filename,-format=>'Format')
Function: Does a new() followed by an fh()
Example : $fh = Bio::SeqIO->newFh(-file=>$filename,-format=>'Format')
$sequence = <$fh>; # read a sequence object
print $fh $sequence; # write a sequence object
Returns : filehandle tied to the Bio::SeqIO::Fh class
Args :
See Bio::SeqIO::Fh
Title : fh
Usage : $obj->fh
Function: Get or set the IO filehandle
Example : $fh = $obj->fh; # make a tied filehandle
$sequence = <$fh>; # read a sequence object
print $fh $sequence; # write a sequence object
Returns : filehandle tied to Bio::SeqIO class
Args : none
Title : next_seq
Usage : $seq = stream->next_seq
Function: Reads the next sequence 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).
Returns : a Bio::Seq sequence object, or nothing if no more sequences
are available
Args : none
See Bio::Root::RootI, Bio::Factory::SeqStreamI, Bio::Seq
Title : write_seq Usage : $stream->write_seq($seq) Function: writes the $seq object into the stream Returns : 1 for success and 0 for error Args : Bio::Seq object
Title : format Usage : $format = $stream->format() Function: Get the sequence format Returns : sequence format, e.g. fasta, fastq Args : none
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'
Title : _load_format_module Usage : *INTERNAL SeqIO stuff* Function: Loads up (like use) a module at run time on demand Example : Returns : Args :
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 :
Title : _filehandle Usage : $obj->_filehandle($newval) Function: This method is deprecated. Call _fh() instead. Example : Returns : value of _filehandle Args : newvalue (optional)
Title : _guess_format
Usage : $obj->_guess_format($filename)
Function: guess format based on file suffix
Example :
Returns : guessed format of filename (lower case)
Args :
Notes : formats that _filehandle() will guess include fasta,
genbank, scf, pir, embl, raw, gcg, ace, bsml, swissprot,
fastq and phd/phred
Title : sequence_factory Usage : $seqio->sequence_factory($seqfactory) Function: Get/Set the Bio::Factory::SequenceFactoryI Returns : Bio::Factory::SequenceFactoryI Args : [optional] Bio::Factory::SequenceFactoryI
Title : object_factory Usage : $obj->object_factory($newval) Function: This is an alias to sequence_factory with a more generic name. Example : Returns : value of object_factory (a scalar) Args : on set, new value (a scalar or undef, optional)
Title : sequence_builder
Usage : $seqio->sequence_builder($seqfactory)
Function: Get/Set the Bio::Factory::ObjectBuilderI used to build sequence
objects. This applies to rich sequence formats only, e.g. genbank
but not fasta.
If you do not set the sequence object builder yourself, it
will in fact be an instance of L<Bio::Seq::SeqBuilder>, and
you may use all methods documented there to configure it.
Returns : a Bio::Factory::ObjectBuilderI compliant object
Args : [optional] a Bio::Factory::ObjectBuilderI compliant object
Title : location_factory
Usage : $seqio->location_factory($locfactory)
Function: Get/Set the Bio::Factory::LocationFactoryI object to be used for
location string parsing
Returns : a Bio::Factory::LocationFactoryI implementing object
Args : [optional] on set, a Bio::Factory::LocationFactoryI implementing
object.
| 2021-08-15 | perl v5.32.1 |