http://wiki.bits.vib.be/index.php/Identify_the_Phred_scale_of_quality_scores_used_in_fastQ
# S - Sanger Phred+33, raw reads typically (0, 40) # X - Solexa Solexa+64, raw reads typically (-5, 40) # I - Illumina 1.3+ Phred+64, raw reads typically (0, 40) # J - Illumina 1.5+ Phred+64, raw reads typically (3, 40) with 0=unused, 1=unused, 2=Read Segment Quality Control Indicator (bold) # L - Illumina 1.8+ Phred+33, raw reads typically (0, 41)
用别人的工具会比价靠谱，自己写容易出错，或考虑不周：
BBMap as a little tool for this:
$ testformat.sh in=N0174.fq.gz
可以这么封装到流程里：
fq1=SRR8501263_1.fastq.gz
fq2=SRR8501263_2.fastq.gz
/home/lizhixin/softwares/bbmap/testformat.sh in=$fq1 | cut -f 1 > fastq.format
# phred=""
for line in $(cat fastq.format); do phred=$line; done
if [ $phred=="sanger" ]
then
echo "sanger"
else
echo "not sanger"
fi
直接用awk命令：
这个对SRA转的fastq无法判断
zcat A14_1.fastq.gz | head -100 | awk '{if(NR%4==0) printf("%s",$0);}' | od -A n -t u1 | awk 'BEGIN{min=100;max=0;}{for(i=1;i<=NF;i++) {if($i>max) max=$i; if($i<min) min=$i;}}END{if(max<=74 && min<59) print "Phred+33"; else if(max>73 && min>=64) print "Phred+64"; else if(min>=59 && min<64 && max>73) print "Solexa+64"; else print "Unknown score encoding!";}'
一个Perl脚本
#!/usr/bin/perl -w
# http://wiki.bits.vib.be/index.php/Identify_the_Phred_scale_of_quality_scores_used_in_fastQ
use strict;
use File::Basename;
use List::MoreUtils qw( minmax );
# fastq_detect.pl fastq.file sample-size
# detect fastQ format from quality scores in fastQ input file
# Version 3
#
# Stephane Plaisance - VIB-BITS - July-04-2012
# Joachim Jacob - Aug-02-2012 - joachim.jacob@gmail.com
# - changed the maximum value of Sanger to 73
# - changed reading the file with a file handle
# (was a file handle !! supporting several archive formats. SP)
# - changed the diagnosing algoritm
# Stephane Plaisance - VIB-BITS - April-08-2013
# - merged both versions and corrected flaw in min/max
# thanks to Sergey Mitrfanov for perl reformatting
#####################################################################
# diagnose
# SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS.....................................................
# ..........................XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX......................
# ...............................IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII......................
# .................................JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ......................
# LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL....................................................
# !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`abcdefghijklmnopqrstuvwxyz{|}~
# | | | | | |
# 33 59 64 73 104 126
# S 0........................26...31.......40
# X -5....0........9.............................40
# I 0........9.............................40
# J 3.....9.............................40
# L 0.2......................26...31........41
#
# S - Sanger Phred+33, raw reads typically (0, 40)
# X - Solexa Solexa+64, raw reads typically (-5, 40)
# I - Illumina 1.3+ Phred+64, raw reads typically (0, 40)
# J - Illumina 1.5+ Phred+64, raw reads typically (3, 40) with 0=unused, 1=unused, 2=Read Segment Quality Control Indicator (bold)
# L - Illumina 1.8+ Phred+33, raw reads typically (0, 41)
#####################################################################
my $script = basename($0);
@ARGV gt 0 or die "usage: $script <fastq file> <opt:sample-size (100)>
";
my ($inputfile, $limit) = @ARGV;
if (! defined $limit) { $limit = 100}; # check first 100 records
my $cnt=0;
my ($min, $max); # global min and max values
# print STDERR "
## Analysing ".$limit." records from $inputfile ...
";
my $z = ReadFile ($inputfile) || die "Error: cannot read from variant file $inputfile: $!
";
## parse
while (my $id = <$z>) {
$id =~ m/^@/ || die "expected @ not found in line 1!
";
my $seq = <$z>;
my $sep = <$z>;
$sep =~ m/^+/ || die "expected + not found in line 3!
";
my $qual = <$z>;
chomp($qual);
$cnt++;
$cnt>=$limit && last;
# char to ascii
my @chars = split("", $qual);
my @nums = sort { $a <=> $b } (map { unpack("C*", $_ )} @chars);
if ($cnt==1) {
($min, $max) = minmax @nums;
} else {
my ($lmin, $lmax) = minmax @nums; # local values for this read
$lmin<$min ? $min=$lmin : $min=$min;
$lmax>$max ? $max=$lmax : $max=$max;
}
}
undef $z;
## diagnose
my %diag=(
'Sanger' => '.',
'Solexa' => '.',
'Illumina 1.3+' => '.',
'Illumina 1.5+' => '.',
'Illumina 1.8+' => '.',
);
my %comment=(
'Sanger' => 'Phred+33, Q[33; 73], (0, 40)',
'Solexa' => 'Solexa+64, Q[59; 104], (-5, 40)',
'Illumina 1.3+' => 'Phred+64, Q[64; 104], (0, 40)',
'Illumina 1.5+' => 'Phred+64, Q[66; 104], (3, 40), with 0=N/A, 1=N/A, 2=Read Segment Quality Control Indicator',
'Illumina 1.8+' => 'Phred+33, Q[33; 74], (0, 41)',
);
if ($min<33 || $max>104) { die "Quality values corrupt. found [$min; $max] where [33; 104] was expected
"; }
if ($min>=33 && $max<=73) {$diag{'Sanger'}='x';}
if ($min>=59 && $max<=104) {$diag{'Solexa'}='x';}
if ($min>=64 && $max<=104) {$diag{'Illumina 1.3+'}='x';}
if ($min>=66 && $max<=104) {$diag{'Illumina 1.5+'}='x';}
if ($min>=33 && $max<=74) {$diag{'Illumina 1.8+'}='x';}
## report
# print STDERR "# sampled raw quality values are in the range of [".$min."; ".$max."]
";
# print STDERR "# format(s) marked below with 'x' agree with this range
";
foreach my $format (sort keys %diag) {
#print STDERR sprintf(" %-13s : %2s [%-30s]
", $format, $diag{$format}, $comment{$format});
if ($diag{$format} eq "x") {print "$format
"}
}
##############
#### Subs ####
# reads from uncompressed, gzipped and bgzip fastQ files
sub ReadFile {
my $infile = shift;
my $FH;
if ($infile =~ /.bz2$/) {
open ($FH, "bzcat $infile |") or die ("$!: can't open file $infile");
} elsif ($infile =~ /.gz$/) {
open ($FH, "zcat $infile |") or die ("$!: can't open file $infile");
} elsif ($infile =~ /.fq|.fastq|.txt$/) {
open ($FH, "cat $infile |") or die ("$!: can't open file $infile");
} else {
die ("$!: do not recognise file type $infile");
}
return $FH;
}