Other approaches using a for-loop are perfectly OK and you should be sure you understand them. But as you gain more experience with Perl, you'll see that there's a good deal of wasted motion there. Here's a solution I find neat and easy to understand — once you understand the powerful map built-in!
c:\@Work\Perl\monks>perl -le
"use warnings;
use strict;
;;
use List::Util qw( min max );
;;
my @not_normalized = qw(5 4 9 9 6);
;;
my @normalized = normalizer(@not_normalized);
;;
printf qq{$_ } for @normalized;
;;
sub normalizer {
my $min_numarray = min @_;
my $max_numarray = max @_;
my $numden = $max_numarray - $min_numarray;
;;
return map { ($_ - $min_numarray) / $numden } @_;
}
"
0.2 0 1 1 0.4
The next thing to understand is that if you are processing a
large array (and what is "large" depends on your circumstances), it may be advantageous to pass (and perhaps return) the array by reference; see
perlref and
perlreftut.
Update: And if you can stand to operate on the elements of the array in place (definitely fastest for large arrays), here's yet another approach:
c:\@Work\Perl\monks>perl -le
"use warnings;
use strict;
;;
use List::MoreUtils qw(minmax);
;;
my @array = qw(5 4 9 9 6);
;;
normalizer(@array);
;;
printf qq{$_ } for @array;
;;
sub normalizer {
return unless @_ >= 2;
my ($min, $max) = minmax @_;
my $numden = $max - $min;
;;
$_ = ($_ - $min) / $numden for @_;
}
"
0.2 0 1 1 0.4
This depends on the
aliasing of the
@_ function argument array. See
perlglossary for a brief discussion of the concept of an
alias. Also see
aliasing in Wikipedia.
Give a man a fish: <%-{-{-{-<
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