changeset 1:20ca2574216a draft default tip

Uploaded

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/fasta-stats.pl	Tue Jun 25 01:51:40 2013 -0400
@@ -0,0 +1,89 @@
+#!/usr/bin/env perl
+
+# fasta-stats
+# written by [e-mail] 
+# oct 2012
+
+use strict;
+use warnings;
+use List::Util qw(sum min max);
+
+# stat storage
+
+my $n=0;
+my $seq = '';
+my %stat;
+my @len;
+
+# MAIN LOOP collecting sequences
+
+while (my $line = <ARGV>) {
+  chomp $line;
+  if ($line =~ m/^\s*>/) {
+    process($seq) if $n;
+    $n++;
+    $seq='';
+  }
+  else {
+    $seq .= $line;
+  }  
+}
+
+process($seq) if $n;
+
+# sort length array 
+# (should use hash here for efficiency with huge no of short reads?)
+
+@len = sort { $a <=> $b } @len;
+
+# compute more stats
+
+$stat{'num_seq'} = scalar(@len);
+
+if (@len) {
+  $stat{'num_bp'} = sum(@len);
+  $stat{'len_min'} = $len[0];
+  $stat{'len_max'} = $len[-1];
+  $stat{'len_median'} = $len[int(@len/2)];
+  $stat{'len_mean'} = int( $stat{'num_bp'} / $stat{'num_seq'} ); 
+  # calculate n50
+
+  $stat{'len_N50'} = 0;
+  my $cum=0;
+  my $thresh = int 0.5 * $stat{'num_bp'};
+  for my $i (0 .. $#len) {
+    $cum += $len[$i];
+    if ($cum >= $thresh) {
+      $stat{'len_N50'} = $len[$i];
+      last;
+    }
+  }
+}
+
+#calculate GC content
+$stat{'num_bp_not_N'} = $stat{'num_G'} + $stat{'num_C'} + $stat{'num_A'} + $stat{'num_T'};
+$stat{'GC_content'} = ($stat{'num_G'} + $stat{'num_C'}) / $stat{'num_bp_not_N'}*100;
+
+# print stats as .tsv
+
+for my $name (sort keys %stat) {
+    if ($name =~ m/GC_content/){
+        printf "%s\t%0.1f\n", $name, $stat{$name};
+    } else {
+        printf "%s\t%s\n", $name, $stat{$name};
+    }
+}
+
+# run for each sequence
+
+sub process {
+  my($s) = @_;
+  # base composition
+  for my $x (qw(A G T C N)) {
+    my $count = $s =~ s/$x/$x/gi;
+    $stat{"num_$x"} += $count;
+  }
+  # keep list of all lengths encountered
+  push @len, length($s);    
+}
+