PERL Beginners - average and standard deviation

Author

average and standard deviation

Mahurshi Akilla

2007-10-03, 7:01 pm

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

Wagner, David --- Senior Programmer Analyst --- WG

2007-10-03, 7:01 pm

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=20
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> -----Original Message-----
> From: Mahurshi Akilla [mailto:mahurshi@gmail.com]=20
> Sent: Wednesday, October 03, 2007 11:18
> To: beginners@perl.org
> Subject: average and standard deviation
>=20
> 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.
>=20
> i saw something for the average (see below). it works fine. is there
> a similar quickie for std deviation (or perhaps, the median)
>=20
> use List::Util qw(sum);
> @array =3D (1, 1.5, 2);
> $average =3D sum(@array)/@array;
> print "$average
>=20
>=20
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 =3D Statistics::Descriptive::Full->new();
$stat->add_data(1, 1.5, 2);=20

my $mean =3D $stat->mean();
my $var =3D $stat->variance();
my $tm =3D $stat->trimmed_mean(.25);
my $std =3D $stat->standard_deviation();
$Statistics::Descriptive::Tolerance =3D 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 ;)
> --=20
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>=20
>=20
>=20

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