news.utdallas.edu!convex!tchrist Tue Dec 15 10:08:26 CST 1992
Article: 64 of comp.lang.perl
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From: Tom Christiansen <tchrist@convex.COM>
#Subject: Re: Statistic routines ?
Originator: tchrist@pixel.convex.com
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Message-ID: <1992Dec15.155017.14450@news.eng.convex.com>
Date: Tue, 15 Dec 1992 15:50:17 GMT
Reply-To: tchrist@convex.COM (Tom Christiansen)
References: <Bz7qCA.Gy5@cosy.sbg.ac.at>
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Organization: Convex Computer Corporation, Colorado Springs, CO
Keywords: statistic
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              Corp. The opinions expressed are those of the user and
              not necessarily those of CONVEX.
Lines: 65

>From the keyboard of lendl@cosy.sbg.ac.at (Otmar Lendl):
:I have to do some statistical analysis of data I gather with
:perl scripts, so it would be convenient to use perl for that
:purpose, too.
:
:Before I start to write my own set of functions (Mean, standard-deviation,
:histograms, ...) I better ask if there are already such beasts.
:I checked the script-archives listed in the FAQs (convex, ohio-state),
:but could not find anything suitable.

Here's something I hacked out yesterday.  The format is 

title<tab>a b c d e

where the letters are the number of scores of value 1..5;

--tom


#/usr/bin/perl
$[ = 1;
while (<>) {
    if (/^\s*$/) {
	print;
	next;
    } 
    $v = $mean = $sum = $n = $sdev = 0;

    ($title, $figures) = /^([^\t]+)\t+(.*)/;
    split(' ',$figures);

    for ($i = 1; $i <= 5; $i++) {
	$n += $_[$i];
	$sum += $i * $_[$i];
    } 

    $mean = $sum / $n;

    for ($i = 1; $i <= 5; $i++) {
	for ($j = 0; $j < $_[$i]; $j++) {
	    $v += ($mean - $i) ** 2;
	} 
    }
    $v /= $n;
    $sdev = sqrt($v);

    write;
    
} 

format STDOUT_TOP = 
Course Title                   N     Mean   Std Dev
==========================    ===    =====  =======
.

format STDOUT = 
@<<<<<<<<<<<<<<<<<<<<<<<<<    @##    @#.##  @#.##
$title,			     $n,     $mean, $sdev
.

-- 
    Tom Christiansen      tchrist@convex.com      convex!tchrist
    Even if you aren't in doubt, consider the mental welfare of the person who
    has to maintain the code after you, and who will probably put parens in
    the wrong place.  --Larry Wall in the perl man page