package Statistics::Lite;
use strict;
use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);
require Exporter;
$VERSION = '2.0';
@ISA = qw(Exporter);
@EXPORT = ();
@EXPORT_OK = qw(min max range sum count mean median mode variance stddev statshash statsinfo);
%EXPORT_TAGS=
(
all => [ @EXPORT_OK ],
funcs => [qw<min max range sum count mean median mode variance stddev>],
stats => [qw<statshash statsinfo>],
);
sub count
{ return scalar @_; }
sub min
{
return unless @_;
return $_[0] unless @_ > 1;
my $min= shift;
foreach(@_) { $min= $_ if $_ < $min; }
return $min;
}
sub max
{
return unless @_;
return $_[0] unless @_ > 1;
my $max= shift;
foreach(@_) { $max= $_ if $_ > $max; }
return $max;
}
sub range
{
return unless @_;
return 0 unless @_ > 1;
return abs($_[1]-$_[0]) unless @_ > 2;
my $min= shift; my $max= $min;
foreach(@_) { $min= $_ if $_ < $min; $max= $_ if $_ > $max; }
return $max - $min;
}
sub sum
{
return unless @_;
return $_[0] unless @_ > 1;
my $sum;
foreach(@_) { $sum+= $_; }
return $sum;
}
sub mean
{
return unless @_;
return $_[0] unless @_ > 1;
return sum(@_)/scalar(@_);
}
sub median
{
return unless @_;
return $_[0] unless @_ > 1;
@_= sort{$a<=>$b}@_;
return $_[$#_/2] if @_&1;
my $mid= @_/2;
return ($_[$mid-1]+$_[$mid])/2;
}
sub mode
{
return unless @_;
return $_[0] unless @_ > 1;
my %count;
foreach(@_) { $count{$_}++; }
my $maxhits= max(values %count);
foreach(keys %count) { delete $count{$_} unless $count{$_} == $maxhits; }
return mean(keys %count);
}
sub variance
{
return unless @_;
return 0 unless @_ > 1;
my $mean= mean @_;
return (sum map { ($_ - $mean)**2 } @_) / scalar(@_);
}
sub stddev
{
return unless @_;
return 0 unless @_ > 1;
return sqrt variance @_;
}
sub statshash
{
return unless @_;
return
(
count => 1,
min => $_[0],
max => $_[0],
range => 0,
sum => $_[0],
mean => $_[0],
median => $_[0],
mode => $_[0],
variance => 0,
stddev => 0,
) unless @_ > 1;
my $count= scalar(@_);
@_= sort{$a<=>$b}@_;
my $median;
if(@_&1) { $median= $_[$#_/2]; }
else { my $mid= @_/2; $median= ($_[$mid-1]+$_[$mid])/2; }
my $sum= 0;
my %count;
foreach(@_) { $sum+= $_; $count{$_}++; }
my $mean= $sum/$count;
my $variance= mean map { ($_ - $mean)**2 } @_;
my $maxhits= max(values %count);
foreach(keys %count)
{ delete $count{$_} unless $count{$_} == $maxhits; }
return
(
count => $count,
min => $_[0],
max => $_[-1],
range => ($_[-1] - $_[0]),
sum => $sum,
mean => $mean,
median => $median,
mode => mean(keys %count),
variance => $variance,
stddev => sqrt($variance),
);
}
sub statsinfo
{
my %stats= statshash(@_);
return <<".";
min = $stats{min}
max = $stats{max}
range = $stats{range}
sum = $stats{sum}
count = $stats{count}
mean = $stats{mean}
median = $stats{median}
mode = $stats{mode}
variance = $stats{variance}
stddev = $stats{stddev}
.
}
1;
__END__
=head1 NAME
Statistics::Lite - Small stats stuff.
=head1 SYNOPSIS
use Statistics::Lite qw(:all);
$min= min @data;
$mean= mean @data;
%data= statshash @data;
print "sum= $data{sum} stddev= $data{stddev}\n";
print statsinfo(@data);
=head1 DESCRIPTION
This module is a lightweight, functional alternative to larger, more complete,
object-oriented statistics packages.
As such, it is likely to be better suited, in general, to smaller data sets.
This is also a module for dilettantes.
When you just want something to give some very basic, high-school-level statistical values,
without having to set up and populate an object first, this module may be useful.
=over 6
=head2 NOTE
This version now uses unbiased estimators (previous versions used biased estimators) for variance and standard deviation.
To get the same biased C<stddev()> and C<variance()> available in previous versions, simply add a zero to the data set:
$stddev_biased= stddev 0, @data;
=back
=head1 FUNCTIONS
=over 4
=item C<min(@data)>, C<max(@data)>, C<range(@data)>, C<sum(@data)>, C<count(@data)>
Return the minimum value, maximum value, range (max - min),
sum, or count of values in C<@data>.
(Count simply returns C<scalar(@data)>.)
=item C<mean(@data)>, C<median(@data)>, C<mode(@data)>
Calculates the mean, median, or mode average of the values in C<@data>.
(In the event of ties in the mode average, their mean is returned.)
=item C<variance(@data)>, C<stddev(@data)>
Return the standard deviation or variance of C<@data>.
=item C<statshash(@data)>
Returns a hash whose keys are the names of all the functions listed above,
with the corresponding values, calculated for the data set.
=item C<statsinfo(@data)>
Returns a string describing the data set, using the values detailed above.
=back
=head2 Import Tags
The C<:all> import tag imports all functions from this module into the
current namespace (use with caution).
To import the individual statistical funcitons, use the import tag C<:funcs>;
use C<:stats> to import C<statshash(@data)> and C<statsinfo(@data)>.
=head1 AUTHOR
Brian Lalonde E<lt>brian@webcoder.infoE<gt>
=head1 SEE ALSO
perl(1).
=cut
