John W. Krahn wrote:
Tom Allison wrote:
John W. Krahn wrote:
Mike Blezien wrote:
what is the most effecient way to combine multiple array refs into one
array ref, IE:
my $arrayrefA = ['1',2','3'];
my $arrayrefB = ['4','5','6'];
my $arrayrefC = ['7','8','9'];
my $allarrayref = (Combine $arrayrefA $arrayrefB $arrayrefC)
So you just want to combine the contents of the anonymous arrays?
my $allarrayref = [ @$arrayrefA, @$arrayrefB, @$arrayrefC ];
You might want to Benchmark this.
I know from the perl cookbook that joining two hashes can be done this
way but it's also mentioned that it is very memory intensive. I don't
know if the same applies here.
My results show that this is not the best way to procede if you are
interested in performance.
use strict;
use warnings;
use Benchmark;
use Time::HiRes;
my $A = [1,2,3,4,5,6,7,8,9];
my $B = [11,12,13,14,15,16,17,18,19];
timethese(10000000,
{
'plain' => 'my $array = [$A, $B];',
'loopy' => 'push @$A, $_ foreach @$B;'
});
Those aren't equivalent. 'plain' is only assigning two scalars while 'loopy'
is pushing nine scalars.
'plain' => 'my $array = [EMAIL PROTECTED], @$B];',
'loopy' => 'push @$array, $_ foreach @$A, @$B;'
But you don't need a foreach loop with push():
'plain' => 'my $array = [EMAIL PROTECTED], @$B];',
'loopy' => 'push @$array, @$A, @$B;'
$ perl -e'
use Benchmark q/cmpthese/;
my $A = [ 1 .. 9 ];
my $B = [ 11 .. 19 ];
cmpthese ( 10_000_000, {
scalar_assign => q/my $array = [ @$A, @$B ]/,
array_assign => q/my $array; @$array = ( @$A, @$B )/,
map_assign => q/my $array; @$array = map @$_, $A, $B/,
push => q/my $array; push @$array, @$A, @$B/,
push_loop1 => q/my $array; push @$array, $_ for @$A, @$B/,
push_loop2 => q/my $array; push @$array, @$_ for $A, $B/,
} );
'
Rate push_loop2 push_loop1 map_assign scalar_assign
array_assign push
push_loop2 550358/s -- -32% -49% -60%
-69% -69%
push_loop1 812348/s 48% -- -25% -40%
-54% -55%
map_assign 1084599/s 97% 34% -- -20%
-38% -40%
scalar_assign 1360544/s 147% 67% 25% --
-23% -24%
array_assign 1757469/s 219% 116% 62% 29%
-- -2%
push 1795332/s 226% 121% 66% 32%
2% --
John
True dat.
But you've shown even better what I was hinting at.
The most "code efficient" method
my $array = [ @$A, @$B ]
is not the most efficient
push @$array, @$_ for $A, $B
that you presented.
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