Re^2: Splicing Arrays on pre-defined indices

[harishnuti]

Thanks a lot for it.. but indeed the above is otherway meaning we are considering indices on what we want rather exclusion , but my requirement is we should exclude certain col by specifying indices( for ex: here @incides)..

my $line = "1!2!3!4!5!6!7!8!9"; # Original line read
my @arr = split /!/, $line;
my @indices = (2,5..8); #i need these indices to be sliced 
print join(" : ", @arr);#original
splice (@arr,@indices,1); # something like this iam trying to achieve 
print "\n";
# i might be having 30 to 40 col of which i dont need 4 to 5, so its b
+etter i slice 4 to 5 col's instead of considering 30 col's

[ikegami]

my @exclude = (2,5..8);
my @exclude_lkup;
$exclude_lkup[$_] = 1 for @exclude;

my $line = "1!2!3!4!5!6!7!8!9";
my @arr = split /!/, $line;

my @filtered = map $arr[$_], grep !$exclude_lkup[$_], 0..$#arr;
print("@filtered\n");  # 1 2 4 5

[harishnuti]

This is awesome, this is what iam looking for....Thx a lot.

[injunjoel]

Since I just updated my previous suggestion I figured I would Benchmark things...
Not that it matters but I thought you might be interested.
Update There was an issue with how I ran the test before. Here are the updated code and results.

#!/usr/bin/perl -w
use strict;
use Benchmark;

my $count = 500000;
my $line = "1!2!3!4!5!6!7!8!9";
my @arr = split /!/, $line;
my @exclude = (2,5..8);
my @exclude_lkup;
$exclude_lkup[$_] = 1 for @exclude;

sub ikegami
{
    my @tarr = @arr;
    my @filtered = map $tarr[$_], grep !$exclude_lkup[$_], 0..$#tarr;
}

sub injun
{
    my @tarr = @arr;
    @tarr[@exclude] = ();
    @tarr = grep $_, @tarr;
}

timethese (
  $count,
  {'Ikegami' => '&ikegami',
   'InjunJoel' => '&injun'}
);

Results in

Benchmark: timing 500000 iterations of Ikegami, InjunJoel...
   Ikegami: 16 wallclock secs (15.88 usr + 0.00 sys = 15.88 CPU) @ 314
+94.08/s (n=500000)
 InjunJoel: 10 wallclock secs ( 11.05 usr + 0.00 sys =  11.05 CPU) @ 4
+5265.25/s (n=500000)

Though I'm not versed enough in O(n) notation to tell you why...

-InjunJoel