#!/usr/bin/perl  -w

# This script reads a Tab-delimited BLAST
# output file, skips lines with E-values
# greater than 1e-20 and prints other lines,
# adding  '**'  for E-values of  zero

# Author: MyName
# Version 2.01   26 Oct 2003
#               added exit(-1)
# Version 2.0    18 Aug 2003
#               get filename as argument
#               pattern match to skip comments
# Version 1.0    01 Feb 2003
#               initial beta version

use strict;
my ($blastfile, $line, $e_value, @cols);

$blastfile = $ARGV[0];
# Verify that an argument was provided
if  (!defined  $blastfile)  {
      print  "Missing filename argument\n";
      print  "Usage: $0  BLAST file\n";
      exit(-1);
}

# Open the BLAST file
open(INFILE, "<$blastfile") or
  die "Cannot open file $blastfile\n";

# Read BLAST results, one line at a time
while  ($line =  <INFILE>)  {
    # Skip comment lines
    if ( $line =~  /^#/ ) { next; }
    @cols = split /\t/, $line;
    $e_value = $cols[10];
   # If e-value begins with 'e', prepend a '1'
   # so Perl can recognize it as an exponential
   # number
    if ( $e_value =~  /^e/ ) {
       $e_value = "1" . $e_value;
    }
   # If e-value is higher than 1e-20, skip
    if ( $e_value > 1e-20 ) { next; }

    if ($e_value  ==  0.0) {
        print "** $line";
    } else {
        print "   $line";
    }
} # End while <INFILE>
close(INFILE);