Re: Speed of Split

I hesitate to mention this, but...

There is currently a minor optimization in split when assigning to a global array. You might give that a try:

local @data;
foreach my $line (@lines) {
   @data = split /\s+/, $line;
   $time = shift @data;
   foreach my $datum (@data) {
   }
}
[download]

untested, untimed.

Comment on Re: Speed of Split Download Code

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Re^2: Speed of Split by Lexicon (Chaplain) on Nov 18, 2004 at 09:53 UTC
Odds are I'll go another route, but out of curiosity, does this speedup hold when assigning to something like @NAMESPACE::data? Lexicon	[reply]
Re^3: Speed of Split by ysth (Canon) on Nov 18, 2004 at 10:09 UTC
Yes, it does. $ perl -MO=Concise,-exec -e'@NAMESPACE::data = split / /, $x' 1 <0> enter 2 <;> nextstate(main 1 -e:1) v 3 </> pushre(/" "/ => @data) s/64 4 <#> gvsv[x] s 5 <$> const[IV 0] s 6 <@> split[t4] vK 7 <@> leave[1 ref] vKP/REFC -e syntax OK $ perl -MO=Concise,-exec -e'@data = split / /, $x' 1 <0> enter 2 <;> nextstate(main 1 -e:1) v 3 </> pushre(/" "/ => @data) s/64 4 <#> gvsv[x] s 5 <$> const[IV 0] s 6 <@> split[t4] vK 7 <@> leave[1 ref] vKP/REFC -e syntax OK $ perl -MO=Concise,-exec -e'my @data; @data = split / /, $x' 1 <0> enter 2 <;> nextstate(main 1 -e:1) v 3 <0> padav[@data:1,2] vM/LVINTRO 4 <;> nextstate(main 2 -e:1) v 5 <0> pushmark s 6 </> pushre(/" "/) s/64 7 <#> gvsv[x] s 8 <$> const[IV 0] s 9 <@> split[t3] lK a <0> pushmark s b <0> padav[@data:1,2] lRM c <2> aassign[t4] vKS d <@> leave[1 ref] vKP/REFC -e syntax OK [download] See above that the array assignment is completely bypassed; instead the array is attached in a funny kind of way to the regex which is then passed to split, and split places the results directly into the array instead of returning them.	[reply] [d/l]
Re^2: Speed of Split by itub (Priest) on Nov 19, 2004 at 01:18 UTC
I also noticed that split in void context, although deprecated, is a little bit faster (or it was the last time I checked). `split; # splits into @_` [download]	[reply] [d/l]


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