### USAGE
# perl -w splitter.pl <filename> <seq-per-file>
# e.g. perl -w splitter.pl nt 20000

### INCLUDES
use strict;
use Bio::SeqIO;

### LOCALS
my $infile	= $ARGV[0];
my $size	= $ARGV[1];
my $i		= 0;
my $j		= 1;

### OBJECT INSTANTIATION
my $in	= Bio::SeqIO->new(
			-file	=> $infile,
			-format	=> 'Fasta',
			);
my $out	= Bio::SeqIO->new(
			-file	=> ">$infile"."_$j.fasta",
			-format	=> 'Fasta',
			);

### PROCESS FILES
while ( my $seq = $in->next_seq() ) {

	$i++;

	if ($i == $size) {
		$j++;
		$out = Bio::SeqIO->new(
					-file	=> ">$infile"."_$j.fasta",
					-format	=> 'Fasta');
		$i = 0;
		}

	$out->write_seq($seq);

	}