I have a script that processes a fair amount of data -- say, 25-50 megs per run. I'd like ideas on speeding it up. The code is actually just a preprocessor -- I'm using another language to do the heavy lifting. But as it happens, the preprocessing takes much more time than the final processing so I'm optimizing this rather than that.
Here's the code. The basic idea is that, for each line of input (redirected to stdin), the program checks to see if the sequence number is in $mult and, if so, prints a line asking the other program to validate that sequence:
Code:
#!/usr/bin/perl -w
open(MULT, "mult.txt") or die("Can't find list of multiplicative sequences in mult.txt");
my $terminator = $/;
undef $/;
$mult = <MULT>;
$/ = $terminator;
// Print application-specific code -- snipped for brevity
$total = 0;
while(<>) {
if (m/(A\d\d\d\d\d\d) ,((-?\d+,)*-?\d+),/) {
$nm = $1;
$seq = $2;
if ($mult =~ /$nm/) { # Replace this line?
print "go(\"$nm\", [$seq]);\n";
$total++;
}
} else {
print "print(\"Error reading line: $_\");\n";
}
}
// Print application-specific code -- snipped for brevity
The file mult.txt is a short file of about a thousand lines, each of which is guaranteed to contain at most (exactly?) one line of the form A\d\d\d\d\d\d; the rest of the line is irrelevant here.
My thought for optimizing this: make an array of the \d\d\d\d\d\d values, sort, and do a binary search rather than a regular expression at the spot marked "Replace this line?". But I'm not sure how to go about that, or even if that's the 'right' optimization. Thoughts?
Also, any suggestions on making better idiomatic use of Perl would be appreciated. I'm not at all accustomed to the language.
I am ASSUMING your mult.txt is something like this:
Code:
A123456
A654321
A024689
A987654
Example 1, As close to your original as possible without waste.
Code:
#!/usr/bin/perl
use strict;
use warnings;
my $total;
my $multfile;
my %multhash;
my @Atmp; # for debugging & education purposes
open($multfile, "<", "mult.txt") or die("Can't find list of multiplicative sequences in mult.txt");
while (<$multfile>) {
chomp;
next if /^$/; # skip blank lines
$multhash{ $_ } = $_; # add to hash, using element as the key & data
}
close($multfile);
@Atmp = (keys %multhash); # for debugging & education purposes
print "@Atmp\n"; # for debugging & education purposes
$total = 0;
while(<>) {
if (m/(A\d\d\d\d\d\d) ,((-?\d+,)*-?\d+),/) {
if (exists $multhash{ $1 }) {
print "go(\"$1\", [$2]);\n";
$total++;
}
} else {
print "print(\"Error reading line: $_\");\n";
}
}
print "Total=$total\n";
Example 2, A bit cleaner
Code:
#!/usr/bin/perl
use strict;
use warnings;
my $total;
my $multfile;
my %multhash;
open($multfile, "<", "mult.txt") or die("Can't find list of multiplicative sequences in mult.txt");
while (<$multfile>) {
chomp;
next if /^$/; # skip blank lines
$multhash{ $_ } = $_; # add to hash, using element as the key & data
}
close($multfile);
$total = 0;
while(<>) {
if (m/(A\d\d\d\d\d\d) ,((-?\d+,)*-?\d+),/ && exists $multhash{ $1 }) {
print "go(\"$1\", [$2]);\n";
$total++;
}
}
print "Total=$total\n";
Example 3, Lean and mean with the need for speed!
NOTE: The regex changes!
Code:
#!/usr/bin/perl
use strict;
use warnings;
my $multfile;
my %multhash;
open($multfile, "<", "mult.txt") or die("Can't find list of multiplicative sequences in mult.txt");
while (<$multfile>) {
chomp;
next if /^$/; # skip blank lines
$multhash{ $_ } = $_; # add to hash, using element as the key & data
}
close($multfile);
while(<>) {
m/(A\d{6}) ,(\d+,\d+)/;
print "go(\"$1\", [$2]);\n" if exists $multhash{ $1 }
}
Hope this gets things going a bit faster for ya!
-Enjoy
fh : )_~
Last edited by Festus Hagen; 09-05-2009 at 12:12 AM..
Reason: regex change Example 3 / Modify #2 for dirty data
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