RE: average and standard deviation

[Wagner, David --- Senior Programmer Analyst --- WGO]

          If you have any problems or questions, please let me know.

     Thanks.

  Wags ;)
David R Wagner
Senior Programmer Analyst
FedEx Freight
1.408.323.4225x2224 TEL
1.408.323.4449           FAX
http://fedex.com/us 
 

> -----Original Message-----
> From: Mahurshi Akilla [mailto:[EMAIL PROTECTED] 
> Sent: Wednesday, October 03, 2007 11:18
> To: beginners@perl.org
> Subject: average and standard deviation
> 
> is there an easy way to get the average and standard deviation in perl
> (given an array of numbers).  i don't want to reinvent the wheel and
> write my own functions.
> 
> i saw something for the average (see below). it works fine.  is there
> a similar quickie for std deviation (or perhaps, the median)
> 
> use List::Util qw(sum);
> @array = (1, 1.5, 2);
> $average = sum(@array)/@array;
> print "$average
> 
> 
You did not state which OS you are running and assuiming you can load
modules, but from ActivePerl for Windows (also on CPAN )
Statistics::Descriptive ( Loaded and took the example from the doc and
ran):
#!perl

use strict;
use warnings;

use Statistics::Descriptive;

my $stat = Statistics::Descriptive::Full->new();
$stat->add_data(1, 1.5, 2); 

my $mean = $stat->mean();
my $var  = $stat->variance();
my $tm   = $stat->trimmed_mean(.25);
my $std  = $stat->standard_deviation();
$Statistics::Descriptive::Tolerance = 1e-10;

printf "Mean: %10.4f  Var: %10.4f  Std Dev: %10.4f  Trimmed mean:
%10.4f\n",
                                $mean,
                                $var ,
                                $std ,
                                $tm  ;
Output:
Mean:     1.5000  Var:     0.2500  Std Dev:     0.5000  Trimmed mean:
1.5000

Wags ;)
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