my $count = 0;
my @every_3rd = grep { ( ++$count % 3 == 0 ) } @array;
-----------------------------------------------------
Dr. Michael K. Neylon - mneylon-pm@masemware.com
||
"You've left the lens cap of your mind on again, Pinky" - The Brain
It's not what you know, but knowing how to find it if you don't know that's important
| [reply]
[d/l] |
Without the extra variable declaration:
my @every_3rd = @array[grep { ! (($_+1) % 3) } 0..$#array];
Update: Fixed (due to jerrygarciuh's catch). Nothing like untested code. And precedence. (though looking at the precedence table in perlop, it looks like what I had (in jerry's node below) should've worked. Bug? Can someone explain?).
Another update:tye explains below. Though I think precedence of parens should differ between 'functions' and 'operators'. Oh well... | [reply]
[d/l] |
Runrig,
Well, maybe I botched it, but all I did was change @array to my var @a like so:
my @a=qw(las vegas every saturday night third is my element);
my @every_3rd = @a[grep { not ($_+1) % 3 } 0..$#a];
print "@every_3rd";
and tell it to print and it runs without error but prints nothing.
???
jg
Ain't no time to hate! Barely time to wait! ~RH | [reply]
[d/l] |
print "$a[$_*3+2] " for (0..$#a/3);
print join ' ', @a[map {$_*3+2} (0..$#a/3)];
Update: Actually if @a has 3N+2 elements, the above two lines will attempt to grab an extra element from beyond the end of the list.... here are the fixed versions:
print "$a[$_*3-1] " for (1..@a/3); print "\n";
print join ' ', @a[map {$_*3-1} (1..@a/3)]; print "\n";
-Blake
| [reply]
[d/l]
[select] |
local $,=' ';
my $i=0;
my @a=qw(las vegas every saturday night third is my element);
print grep { ! (++$i %3) } @a;
prints "every third element";
-- stefp | [reply]
[d/l] |
for ($i=0; $i < @a; $i += 3) {
print "$a[$i] ";
}
conv
| [reply]
[d/l] |
| [reply] |
I noticed that too.... easy fix though, replace $i=0 with $i=2. As written, the code gives you every third word, but it doesn't start on the "correct" one.
-Blake
| [reply]
[d/l]
[select] |
Well, I realize that this has been answered to death, but heres
a solution along a very different line, which also offers some extra flexibility.
#!/usr/local/bin/perl -w
use strict;
use Tie::Cycle;
$\=$/;
my @a=qw(want vegas every first night third array my element);
tie my $ok,'Tie::Cycle',[0,0,1];
$ok && print $_ foreach @a;
The flexibility of this approach can be seen by changing [0,0,1] to [1,0,1].
Of course I'm not really sure why anyone would _want_ to do anything like this, but you never know what'll come up...
:-)
Yves
--
You are not ready to use symrefs unless you already know why they are bad. -- tadmc (CLPM) | [reply]
[d/l]
[select] |