Perl script to extract part of some numbers - perl

Question

I wrote a Perl script that reads from a file and do so calculations. Basically I 'm trying to calculate the Throughput of network traffic. The file I'm reading from has the following format:
- 0.152416 1 2 tcp 1040 ------- 2 12.0 2.9 2 13
r 0.153584 1 2 tcp 1040 ------- 2 12.0 2.9 1 12
+ 0.154208 1 2 tcp 1040 ------- 2 10.0 2.7 3 15
- 0.154208 1 2 tcp 1040 ------- 2 11.0 2.8 3 15
r 0.155248 1 2 tcp 1040 ------- 2 12.0 2.9 2 13
I'm extracting column[0] , [3], [7], [8], [9]. Since column [8] and [9] comes as double (i.e. x.y), I was trying to get only the first part of column[8] and [9] (i.e x part). In other words, I don't care about the second part that comes after the dot "." . All I need the first part. I guess, I have two ways, whether to deal with regular expressions or add more extra code to customize the token in [8] and [9] for each line I will read?. Any short suggestion. part of the script:
#input parameters:
$infile=$ARGV[0];
$dest=$ARGV[1];
$from=$ARGV[2];
$to=$ARGV[3];
$fId=$ARGV[4];
$TimeShift=$ARGV[5];
I want to make $from and $to contains only the first part.
open (DATA,"<$infile") || die "error in $infile $!";
while (<DATA>)
{
#x = split(' '); Im using space

Answer 1

What about
$from = int $ARGV[2];
See int for details.
Or, rather,
my ($infile, $dest, $from, $to, $fId, $TimeShift) = #ARGV;
$_ = int for $from, $to;

Answer 2

You should be aware though, that while you can use int, that it has some dangerous caveats.
From perldoc -f int:
You should not use this function for rounding: one because
it truncates towards 0, and two because machine representations
of floating-point numbers can sometimes produce
counterintuitive results. For example, "int(-6.725/0.025)"
produces -268 rather than the correct -269; that's because it's
really more like -268.99999999999994315658 instead. Usually,
the "sprintf", "printf", or the "POSIX::floor" and
"POSIX::ceil" functions will serve you better than will int().
Instead, consider doing:
using POSIX;
...
...
$from = POSIX::floor($ARGV[2]);

Answer 3

If you just want to throw away the dots and following digits, you can use s/[.][0-9]+\z//. That way, no floating point conversions would be involved.
#!/usr/bin/env perl
use strict; use warnings;
use Data::Dumper;
while (my $line = <DATA>) {
last unless $line =~ /\S/;
my #cols = (split ' ', $line)[0, 3, 7 .. 9];
s/[.][0-9]+\z// for #cols[-2 .. -1];
print Dumper \#cols;
}
__DATA__
- 0.152416 1 2 tcp 1040 ------- 2 12.0 2.9 2 13
r 0.153584 1 2 tcp 1040 ------- 2 12.0 2.9 1 12
+ 0.154208 1 2 tcp 1040 ------- 2 10.0 2.7 3 15
- 0.154208 1 2 tcp 1040 ------- 2 11.0 2.8 3 15
r 0.155248 1 2 tcp 1040 ------- 2 12.0 2.9 2 13