Finding sentences that start off the same with Perl

Directives

use strict; use warnings;

Parse the input

while () { # Ignore commented lines. next if /^#/;

# If the line is blank, just output a line break.
if (/^s*$/)
{
	print "n";
	next;
}

# Clean up the line and get rid of the newlines.
s/^s*//sg;
s/s*$//sg;

# First split the line on the periods. It isn't perfect, but
# should give a rough sentence start.
my @sentances = split(/.s+/);
my @counts = ();

foreach my $sentance (@sentances)
{
	# For each sentence, we split apart the spaces to get the words.
	my @words = split(/s+/, $sentance);

	# Figure out how many words are in the sentences.
	my $count = scalar(@words);
	push @counts, $count;

	# We only care about the first five words in the sentence.
	my @prefix = splice(@words, 0, 5);

	# Print out the sentence and its length. We also include the
	# line number so we can easily jump to that line.
	print "$.: ", join(" ", @prefix), " ($count)n";
}

# Calculate the std. dev. for the counts. If there is a small
# average, then we have too much of a consistent sentence length.

# Put in a summary for the paragraph.
my $stddev = stddev(@counts);

if ($stddev > 0)
{
	printf(
		"-- %d sentences, %.1f median, %.1f stddevn",
		scalar(@counts),
		median(@counts),
		stddev(@counts));
}

}

sub median { # Get a total of all the counts. my $total = 0;

foreach (@_)
{
	$total += $_;
}

# Average it out by dividing by the number of elements.
my $average = $total / scalar(@_);
return $average;

}

sub stddev { # StdDev doesn't mean anything with no elements, so just return 0. return 0 if @_ <= 1;

# Figure out the median value.
my $average = median(@_);

# Figure out the total of the squares differences from the median.
my $total = 0;

foreach (@_)
{
	$total += ($average - $_) ** 2;
}

# Calculate the StdDEv and return it.
my $std = ($total / (@_ - 1)) ** 0.5;
return $std;

}