Re^4: Unpacking and converting

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Re^5: Unpacking and converting by BrowserUk (Patriarch) on Feb 16, 2011 at 15:51 UTC
Thank you for giving me my D'oh moment for today. Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^5: Unpacking and converting by dwalin (Monk) on Feb 16, 2011 at 14:01 UTC
The shifting of elements from the array makes it empty after first iteration. Ugh, I seem to be extra stupid today. But hey, it's not that easy still: `my @s = '0001' .. '1000'; cmpthese -1,{ d => q[ my @d = @s; ], c => q[ my @c = @s; $c[ $_ ] += 0 for 0 .. $#c; ], a => q[ my @a = @s; $_ += 0 for @a; ], b => q[ my @b = @s; my @new; push @new, $_ + 0 while defined( $_ = + shift @b ) ], };` [download] Yields: `Rate c a b d c 793688/s -- -59% -59% -84% a 1941807/s 145% -- -0% -60% b 1942492/s 145% 0% -- -60% d 4812084/s 506% 148% 148% --` [download] So what do we have, shifting and for (@list) are equally fast? Not so: `my @s = '0000001' .. '1000000'; cmpthese -1,{ d => q[ my @d = @s; ], c => q[ my @c = @s; $c[ $_ ] += 0 for 0 .. $#c; ], a => q[ my @a = @s; $_ += 0 for @a; ], b => q[ my @b = @s; my @new; push @new, $_ + 0 while defined( $_ = + shift @b ) ], };` [download] Gives these results: `Rate c b a d c 764586/s -- -58% -62% -85% b 1803742/s 136% -- -10% -65% a 2007409/s 163% 11% -- -61% d 5119310/s 570% 184% 155% --` [download] Which is logical, at last. Scandal of the century is averted, I stand corrected - the only thing I have to find out is why my tests on actual data consistently show shifting to be faster than for (@list). Not several orders of magnitude faster as it was in that faulty benchmark but considerably so. I believe I have to look for an error... Regards, Alex.	[reply] [d/l] [select]