On 2022-01-15 00:04, Jon Smart wrote:
Hello Paul
Do you mean by undef $/ and with <$fh> we can read the file into memory
at one time?
$/ is the input record separator, newline by default.
If undefined that means that the whole file is treated as one single record.
Yes that would be faster b/c we don't need to read file by each line,
which increases the disk IO.
Another questions:
1. what's the "truss" command?
truss is a "unix" command. Search for "truss unix".
2. what's the syntax "<:mmap"?
mmap enables a memory mapped file. I treats the file as if it were a
chunk of memory instead of a file.
Depending on the size of the file and the amount of memory available it
may not make a difference. Benchmark to confirm.
On 15.01.2022 15:45, Paul Procacci wrote:
-------------------------------------
use strict;
$/ = undef;
That is usually written as:
local $/;
because $/ is a global variable and you want to limit the scope of any
change.
my %stopwords = do {
open my $fh, '<:mmap', 'stopwords.txt' or die $!;
map { $_ => 1; } split /\n/, <$fh>;
};
my %count = do {
my %res;
open my $fh, '<:mmap', 'words.txt' or die $!;
map { $res{$_}++ unless $stopwords{$_}; } split /\n/, <$fh>;
%res;
};
my $i=0;
for (sort {$count{$b} <=> $count{$a}} keys %count) {
if ($i < 20) {
print "$_ -> $count{$_}\n"
} else {
last;
}
$i ++;
}
John
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