eliminate empty files in a subroutine in perl - perl

Question

I want to a add a code in the next script to eliminate those empty output files.
The script convert a single fastq file or all the fastq files in a folder to fasta format, all the output fasta files keep the same name of the fastq file; the script present an option to exclude all the sequences that present a determinate number of NNN repeats (NNNNNNNNNNNNNNNNNNATAGTGAAGAATGCGACGTACAGGATCATCTA), I added this option because some sequences present only NNNNN in the sequences, example: if the -n option is equal to 15 (-n 15) it will exclude all the sequences that present 15 o more N repeats, to this point the code works well, but it generate an empty files (in those fastq files that all the sequences present 15 or more N repeats are excluded). I want to eliminate all the empty files (without sequences) and add a count of how many files were eliminate because it were empty.
Code:
#!/usr/bin/env perl
use strict;
use warnings;
use Getopt::Long;
my ($infile, $file_name, $file_format, $N_repeat, $help, $help_descp,
$options, $options_descrp, $nofile, $new_file, $count);
my $fastq_extension = "\\.fastq";
GetOptions (
'in=s' => \$infile,
'N|n=i' =>\$N_repeat,
'h|help' =>\$help,
'op' =>\$options
);
# Help
$help_descp =(qq(
Ussaje:
fastQF -in fastq_folder/ -n 15
or
fastQF -in file.fastq -n 15
));
$options_descrp =(qq(
-in infile.fastq or fastq_folder/ required
-n exclude sequences with more than N repeat optional
-h Help description optional
-op option section optional
));
$nofile =(qq(
ERROR: "No File or Folder Were Chosen !"
Usage:
fastQF -in folder/
Or See -help or -op section
));
# Check Files
if ($help){
print "$help_descp\n";
exit;
}
elsif ($options){
print "$options_descrp\n";
exit;
}
elsif (!$infile){
print "$nofile\n";
exit;
}
#Subroutine to convert from fastq to fasta
sub fastq_fasta {
my $file = shift;
($file_name = $file) =~ s/(.*)$fastq_extension.*/$1/;
# eliminate old files
my $oldfiles= $file_name.".fasta";
if ($oldfiles){
unlink $oldfiles;
}
open LINE, '<', $file or die "can't read or open $file\n";
open OUTFILE, '>>', "$file_name.fasta" or die "can't write $file_name\n";
while (
defined(my $head = <LINE>) &&
defined(my $seq = <LINE>) &&
defined(my $qhead = <LINE>) &&
defined(my $quality = <LINE>)
) {
substr($head, 0, 1, '>');
if (!$N_repeat){
print OUTFILE $head, $seq;
}
elsif ($N_repeat){
my $number_n=$N_repeat-1;
if ($seq=~ m/(n)\1{$number_n}/ig){
next;
}
else{
print OUTFILE $head, $seq;
}
}
}
close OUTFILE;
close LINE;
}
# execute the subrutine to extract the sequences
if (-f $infile) { # -f es para folder !!
fastq_fasta($infile);
}
else {
foreach my $file (glob("$infile/*.fastq")) {
fastq_fasta($file);
}
}
exit;
I have tried to use the next code outside of the subroutine (before exit) but it just work for the last file :
$new_file =$file_name.".fasta";
foreach ($new_file){
if (-z $new_file){
$count++;
if ($count==1){
print "\n\"The choosen File present not sequences\"\n";
print " \"or was excluded due to -n $N_repeat\"\n\n";
}
elsif ($count >=1){
print "\n\"$count Files present not sequences\"\n";
print " \" or were excluded due to -n $N_repeat\"\n\n";
}
unlink $new_file;
}
}
and I just have tried something similar inside of the subroutine but this last code don´t work !!!!
Any Advise !!!!???
Thanks So Much !!!

Answer 1

you should check, if something was written to your new file at the end of our fastq_fasta subroutine. Just put your code after the close OUTFILE statement:
close OUTFILE;
close LINE;
my $outfile = $file_name.".fasta";
if (-z $outfile)
{
unlink $outfile || die "Error while deleting '$outfile': $!";
}
Additionally, it will be better to add the die/warn statement also to the other unlink line. Empty files should be deleted.
Maybe another solution if you are not fixed to perl, but allowed to use sed and a bash loop:
for i in *.fastq
do
out=$(dirname "$i")/$(basename "$i" .fastq).fasta
sed -n '1~4{s/^#/>/;N;p}' "$i" > "$out"
if [ -z $out ]
then
echo "Empty output file $out"
rm "$out"
fi
done
Hope that helps!
Best Frank

Answer 2

The easiest thing to do is probably to add a counter to your subroutine to keep track of the number of sequences in the outfile:
sub fastq_fasta {
my $counter1 = 0;
my $file = shift;
($file_name = $file) =~ s/(.*)$fastq_extension.*/$1/;
# eliminate old files
my $oldfiles= $file_name.".fasta";
if ($oldfiles){
unlink $oldfiles;
}
open LINE, '<', $file or die "can't read or open $file\n";
open OUTFILE, '>>', "$file_name.fasta" or die "can't write $file_name\n";
while (
defined(my $head = <LINE>) &&
defined(my $seq = <LINE>) &&
defined(my $qhead = <LINE>) &&
defined(my $quality = <LINE>)
) {
$counter1 ++;
substr($head, 0, 1, '>');
if (!$N_repeat){
print OUTFILE $head, $seq;
}
elsif ($N_repeat){
my $number_n=$N_repeat-1;
if ($seq=~ m/(n)\1{$number_n}/ig){
$counter1 --;
next;
}
else{
print OUTFILE $head, $seq;
}
}
}
close OUTFILE;
close LINE;
return $counter1;
}
You can then delete files when the returned count is zero:
if (-f $infile) { # -f es para folder !!
fastq_fasta($infile);
}
else {
foreach my $file (glob("$infile/*.fastq")) {
if (fastq_fasta($file) == 0) {
$file =~ s/(.*)$fastq_extension.*/$1.fasta/;
unlink $file;
}
}
}