How can I convert a number to its multiple form in Perl? - perl

Question

Do you know an easy and straight-forward method/sub/module which allows me to convert a number (say 1234567.89) to an easily readable form - something like 1.23M?
Right now I can do this by making several comparisons, but I'm not happy with my method:
if($bytes > 1000000000){
$bytes = ( sprintf( "%0.2f", $bytes/1000000000 )). " Gb/s";
}
elsif ($bytes > 1000000){
$bytes = ( sprintf( "%0.2f", $bytes/1000000 )). " Mb/s";
}
elsif ($bytes > 1000){
$bytes = ( sprintf( "%0.2f", $bytes/1000 )). " Kb/s";
}
else{
$bytes = sprintf( "%0.2f", $bytes ). "b/s";
}
Thank you for your help!

Answer 1

The Number::Bytes::Human module should be able to help you out.
An example of how to use it can be found in its synopsis:
use Number::Bytes::Human qw(format_bytes);
$size = format_bytes(0); # '0'
$size = format_bytes(2*1024); # '2.0K'
$size = format_bytes(1_234_890, bs => 1000); # '1.3M'
$size = format_bytes(1E9, bs => 1000); # '1.0G'
# the OO way
$human = Number::Bytes::Human->new(bs => 1000, si => 1);
$size = $human->format(1E7); # '10MB'
$human->set_options(zero => '-');
$size = $human->format(0); # '-'

Answer 2

Number::Bytes::Human seems to do exactly what you want.

Answer 3

sub magnitudeformat {
my $val = shift;
my $expstr;
my $exp = log($val) / log(10);
if ($exp < 3) { return $val; }
elsif ($exp < 6) { $exp = 3; $expstr = "K"; }
elsif ($exp < 9) { $exp = 6; $expstr = "M"; }
elsif ($exp < 12) { $exp = 9; $expstr = "G"; } # Or "B".
else { $exp = 12; $expstr = "T"; }
return sprintf("%0.1f%s", $val/(10**$exp), $expstr);
}

Answer 4

In pure Perl form, I've done this with a nested ternary operator to cut on verbosity:
sub BytesToReadableString($) {
my $c = shift;
$c >= 1073741824 ? sprintf("%0.2fGB", $c/1073741824)
: $c >= 1048576 ? sprintf("%0.2fMB", $c/1048576)
: $c >= 1024 ? sprintf("%0.2fKB", $c/1024)
: $c . "bytes";
}
print BytesToReadableString(225939) . "/s\n";
Outputs:
220.64KB/s

Answer 5

This snippet is in PHP, and it's loosely based on some example someone else had on their website somewhere (sorry buddy, I can't remember).
The basic concept is instead of using if, use a loop.
function formatNumberThousands($a,$dig)
{
$unim = array("","k","m","g");
$c = 0;
while ($a>=1000 && $c<=3) {
$c++;
$a = $a/1000;
}
$d = $dig-ceil(log10($a));
return number_format($a,($c ? $d : 0))."".$unim[$c];
}
The number_format() call is a PHP library function which returns a string with commas between the thousands groups. I'm not sure if something like it exists in perl.
The $dig parameter sets a limit on the number of digits to show. If $dig is 2, it will give you 1.2k from 1237.
To format bytes, just divide by 1024 instead.
This function is in use in some production code to this day.