#!/usr/bin/env perl
# Strictly a filter, this histograms incoming data points into requested bin sizes.  If
# bin sizes are not given with the -interval option, then the interval is assumed to be
# max-min/10
# &: Jan 28, 2003
#
use strict;
use warnings;
use POSIX qw(floor ceil);

my $IntervalWidth = undef;
my $UseStar = undef;         # Print horiz histogram with hash-marks
my $Scale = 1;               # If $UseStar, each * represents a count of this much.

while (my $arg = shift(@ARGV)) {
  if ($arg =~ /^-h(elp)?$/) {
    usage();
  } elsif ($arg =~ /^-int/) {
    $IntervalWidth = shift(@ARGV);
  } elsif ($arg =~ /^-star/) {
    $UseStar = 1;
  } elsif ($arg =~ /^-scale/) {
    $Scale = shift(@ARGV);
  } elsif ($arg =~ /^-/) {
    print STDERR "Unknown option: $arg\n";
    usage();
  } else {
    last;
  }
}
die "You need to specify the Interval Width (bucket size) with -int in this version" if !$IntervalWidth || $IntervalWidth < 0;

my ($min, $max);
my ($sum, $sumSq, $num) = (0,0,0);
my %bins;
while (my $line = <STDIN>) {
  my @f = split(/\s+/, $line);
  foreach my $val (@f) {
    next if $val =~ /^\s*$/;

    $max = $val if (!defined($max) || $max < $val);
    $min = $val if (!defined($min) || $min > $val);
    $sum += $val;
    $sumSq += $val * $val;
    $num++;

    # Increment the right bin
    #
    my $bin = floor($val/$IntervalWidth);
    $bins{$bin}++;

    print STDERR "$num\r" if ($num %100000 == 0);
    print STDERR "$num\n" if ($num %1000000 == 0);
  }
}
exit(0) if !defined($min) || !defined($max);

# Misc Stats
my $mean = $num == 0? 0 : $sum/$num;
my $var = $num == 0? 0 : $sumSq/$num - $mean * $mean;
my $sd = sqrt($var);

$Scale = 1 if ($Scale <= 0);
print "# NumSamples = $num; Max = $max; Min = $min\n";
print "# Mean = $mean; Variance = $var; SD = $sd\n";
print "# Each * represents a count of $Scale\n" if ($UseStar);
  
for (my $i = 0; $min+$i*$IntervalWidth < $max; $i++) {
  $bins{$i} = 0 if !$bins{$i};
  my $low = $min + $i*$IntervalWidth;
  my $hi = $min + ($i+1)*$IntervalWidth;
  my $tag = sprintf("%.4f - %.4f", $low, $hi);
  if ($UseStar && $Scale != 0) {
    printf "%20s [%6d]: %s\n", "$tag", $bins{$i}, getStringOfLength($bins{$i}/$Scale);
  } else {
    printf "%20s: %d\n", "$tag", $bins{$i};
  }
}
  
#----------------------------------------------------------------------

sub getStringOfLength {
  my($n) = @_;
  my $s = "";
  
  for (my $j = 0; $j < $n; $j++) {
    $s .= "*";
  }
  return $s;
}  

sub usage {
  print "Usage: histo [-help] [-interval num] [-stars]\n";
  print "Strictly a filter, this histograms incoming numerical data points into\n" .
      "requested bin sizes.  If bin sizes are not given with the -interval\n" .
      "option, then the interval is assumed to be max-min/10.\n";
  print "Use -stars to print a horizontal bar of stars for each bin\n";
  exit 1;
}