Re: Match Numeric Range

PilotinControl:

If you're just wanting to simplify conditional statements like the ones you've shown, I typically use a function like this:

use strict;
use warnings;

sub between {
   my ($min, $val, $max) = @_;
   return $val>=$min && $val<=$max;
}

for my $range (450, 475, 500, 550, 450, 350, 250, 100) {
    print "Range: $range\n";
    if (between(300, $range, 400)) {
        exit;
    }
    if (between(425, $range, 500)) {
        print "LIGHTS ON\n";
    }
}
[download]

$ perl t.pl
Range: 450
LIGHTS ON
Range: 475
LIGHTS ON
Range: 500
LIGHTS ON
Range: 550
Range: 450
LIGHTS ON
Range: 350
[download]

If you need to get fancier and build your functions dynamically (such as reading the values from a file), I tend to use a closure to generate them:

#!/usr/bin/env perl
use strict;
use warnings;

# Build the functions
my @tests;
while (<DATA>) {
    my ($min, $max, $message) = split /\s+/, $_, 3;
    push @tests, make_test_function($min, $max, $message);
}

my $range = 0;
while ($range < 600) {
    print "Range: $range\n";
    for my $test (@tests) {
        $test->($range);
    }
    $range += int(100*rand);
}

sub make_test_function {
    my ($min, $max, $message) = @_;
    return sub {
        my $val = shift;
        print $message if $val >= $min and $val <= $max;
    }
}

__DATA__
100 350  In range A
200 500  In range B
300 400  In range C
[download]

$ perl t.pl
Range: 0
Range: 10
Range: 10
Range: 25
Range: 56
Range: 144
In range A
Range: 208
In range A
In range B
Range: 254
In range A
In range B
Range: 323
In range A
In range B
In range C
Range: 379
In range B
In range C
Range: 468
In range B
Range: 530
Range: 550
Range: 557
[download]

...roboticus

When your only tool is a hammer, all problems look like your thumb.

Comment on Re: Match Numeric Range Select or Download Code

Replies are listed 'Best First'.
Re^2: Match Numeric Range by PilotinControl (Pilgrim) on Aug 18, 2015 at 13:53 UTC
Thanks roboticus...the script is looking for the range of numbers dynamically in real time: 400-500 = Lights Off and 200-300 = Lights On. These numbers are generated via the photo resistor and is read from the serial port. The script is turned on and runs in the backround and once one of those numbers in the specified range has been detected the lights will either turn on or turn off. The while loop freezes my script as its looking for the range of numbers. The loops needs to continually be checking for that range of numbers as it will eventually trigger other things to happen.	[reply]
Re^3: Match Numeric Range by Your Mother (Archbishop) on Aug 18, 2015 at 14:14 UTC
This kind of thing can be okay for progressive checking. I normal dislike this style of code/logic but it seems a good fit for this kind of problem. `if ( $range > 500 ) { WAT_OP(); } elsif ( $range >= 425 ) { some_op(); } elsif ( $range > 400 ) { some_other_op(); } elsif ( $range > 300 ) { exit 0; } else { complete_tree_op(); }` [download] You can also do something more dispatchy– `my @action_tree = ( { test => sub { $_[0] >= 300 && $_[0] <= 400 }, action => sub { print "GUDNITES\n"; CORE::exit(0 +) } }, { test => sub { $_[0] >= 425 && $_[0] <= 500 }, action => sub { print "OHAI\n" } } ); while ( my $signal = <SIGNAL_SOURCE> ) { $_->{test}->($signal) && $_->{action}->() for @action_tree; }` [download] I'm not advocating either, or that second style of terseness, or any style or approach for that matter. Just expanding the library of options. :P	[reply] [d/l] [select]
Re^4: Match Numeric Range by PilotinControl (Pilgrim) on Aug 18, 2015 at 14:39 UTC
Thanks YourMother! This approach worked as expected and with narrowing down the numbers being sent out by the serial monitor I can fine tune the range of the photo resistor to accomplish what I need it too. Thanks to all who answered.	[reply]


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