Re^2: A locale independent sprintf?

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Re^3: A locale independent sprintf? by kcott (Archbishop) on Jul 29, 2020 at 03:37 UTC
Using `y/,/./`, instead of `s/,/./`, should be faster (see "perlperf: Search and replace or tr"). Obviously, I can't say whether it will be noticeably or usefully faster. You may want the 'r' modifier. Here's a somewhat fudged example for demonstration purposes: `$ perl -E 'say sprintf("3,%d", 14)' 3,14 $ perl -E 'say sprintf("3,%d", 14) =~ y/,/./' Can't modify constant item in transliteration (tr///) at -e line 1, at + EOF Execution of -e aborted due to compilation errors. $ perl -E 'say sprintf("3,%d", 14) =~ y/,/./r' 3.14` [download] If you try this, I'd be interested in what sort of speed improvement you see. — Ken	[reply] [d/l] [select]
Re^4: A locale independent sprintf? by swl (Parson) on Jul 29, 2020 at 04:06 UTC
Good point. I'll see if I can set up some benchmarking and post the results. Update: Running the code below under ubuntu bash under windows with LC_NUMERIC set to de_DE.iso88591 indicates that s///r is about 20% faster than y//r. Both are in the order of millions per second, though. And as yet another update, the order does switch between runs so it's not a consistent outcome. Results: `de_DE.iso88591 3,1 3.1 3.1 Rate y_sprintf s_sprintf sprintf y_sprintf 4646523/s -- -19% -63% s_sprintf 5721423/s 23% -- -54% sprintf 12396265/s 167% 117% --` [download] Code: use Benchmark qw {:all}; use 5.016; local $\| = 1; use POSIX qw /locale_h/; use locale; print POSIX::setlocale(LC_NUMERIC) . "\n"; my $x; $x = sprintf "%.2g", 3.14; print "$x\n"; $x = sprintf ("%.2g", 3.14) =~ y/,/./r; print "$x\n"; $x = sprintf ("%.2g", 3.14) =~ s/,/./r; print "$x\n"; cmpthese ( -3, { sprintf => 'use strict; use warnings; my $x = sprintf ("%.2g +", 3.14)', y_sprintf => 'use strict; use warnings; my $x = sprintf ("%.2g +", 3.14) =~ y/,/./r', s_sprintf => 'use strict; use warnings; my $x = sprintf ("%.2g +", 3.14) =~ s/,/./r', } ); [download] (post was further updated to distinguish results from code)	[reply] [d/l] [select]
Re^5: A locale independent sprintf? by kcott (Archbishop) on Jul 29, 2020 at 09:05 UTC
Interesting and surprising results. You said "the order does switch between runs" but I don't see that in any of the results you posted; there is quite a substantial fluctuation though (`11%` to `65%`). I tried with something closer to the code in perlperf to which I linked earlier. I have Cygwin on Win10. I also have Perlbrew. I originally ran under 5.32.0; then switched to 5.30.0 to match your version — there were no significant differences in results. As my locale uses '.', not ',', I simply swapped the substitution (`y/./,/` instead of `y/,/./`). Here's the code I used: `#!/usr/bin/env perl use 5.016; use warnings; use Benchmark 'cmpthese'; use POSIX 'locale_h'; say POSIX::setlocale(LC_NUMERIC); say sprintf('%.2g', 3.14); say sprintf('%.2g', 3.14) =~ s/\./,/r; say sprintf('%.2g', 3.14) =~ y/./,/r; cmpthese 0 => { sprintf => sub { my $str = sprintf('%.2g', 3.14); return $str; }, y_sprintf => sub { my $str = sprintf('%.2g', 3.14) =~ y/./,/r; ret +urn $str; }, s_sprintf => sub { my $str = sprintf('%.2g', 3.14) =~ s/\./,/r; re +turn $str; }, };` [download] Here's a typically result: `$ ./pm_11119934_bench_locale_s_y.pl en_AU.UTF-8 3.1 3,1 3,1 Rate s_sprintf y_sprintf sprintf s_sprintf 2940825/s -- -46% -85% y_sprintf 5493603/s 87% -- -72% sprintf 19713322/s 570% 259% --` [download] I ran it 5 times with 5.32.0, then 5 times with 5.30.0. The `87%` in the representative run only ranged between `85%` and `89%` in all runs. So, I'm getting `y///` almost twice as fast as `s///`; compared with your `s///` being variably faster than `y///`. I added in the '`use strict; use warnings;`' which you had. Now the results varied (85% 88% 21% 71% 75%) but 'y_sprintf' was still always faster. (I suspect the 21% is bogus — perhaps some short-lived background process fired up at that time.) I then added the '`use locale;`' that you had and this substantially slowed down processing: 'y_sprintf' was still faster than 's_sprintf' but I wouldn't say significantly so (5% 1% 7% 12% 8%). I next replaced my subs with your strings (',' and '.' swapped as before). Again, 'y_sprintf' was faster and this time closer to, albeit more spread out than, my original results (75% 89% 87% 92% 90%). So, I can't replicate your `s///` being faster than `y///`; all my tests indicated that the opposite was the case. I think the addition of '`use strict; use warnings;`' was probably unnecessary for the benchmark; and perhaps a distraction. I don't know enough about locales to confidently comment; however, it would seem that if you can live without '`use locale;`' that would be a good thing (its doco, locale, has warnings about its use). Perhaps try with some of my variations to see if you get different results. — Ken	[reply] [d/l] [select]
Re^6: A locale independent sprintf? by swl (Parson) on Jul 29, 2020 at 12:18 UTC
Re^6: A locale independent sprintf? by swl (Parson) on Jul 29, 2020 at 11:58 UTC
Re^5: A locale independent sprintf? by swl (Parson) on Jul 29, 2020 at 05:11 UTC
Some extra runs while not interacting with the machine. Perl is 5.30.0 via perlbrew under WSL. `perl -v \| head -2 \| tail -1 This is perl 5, version 30, subversion 0 (v5.30.0) built for x86_64-li +nux` [download] Results: de_DE.iso88591 3,1 3.1 3.1 Rate y_sprintf s_sprintf sprintf y_sprintf 4716774/s -- -33% -63% s_sprintf 7052758/s 50% -- -45% sprintf 12712918/s 170% 80% -- Rate y_sprintf s_sprintf sprintf y_sprintf 4816895/s -- -34% -61% s_sprintf 7286043/s 51% -- -41% sprintf 12366711/s 157% 70% -- Rate y_sprintf s_sprintf sprintf y_sprintf 4919055/s -- -32% -70% s_sprintf 7182801/s 46% -- -55% sprintf 16134317/s 228% 125% -- Rate y_sprintf s_sprintf sprintf y_sprintf 4694110/s -- -31% -65% s_sprintf 6766241/s 44% -- -50% sprintf 13495072/s 187% 99% -- Rate y_sprintf s_sprintf sprintf y_sprintf 4661016/s -- -36% -70% s_sprintf 7310428/s 57% -- -53% sprintf 15604067/s 235% 113% -- Rate y_sprintf s_sprintf sprintf y_sprintf 5036750/s -- -10% -62% s_sprintf 5583036/s 11% -- -58% sprintf 13364520/s 165% 139% -- Rate y_sprintf s_sprintf sprintf y_sprintf 4737843/s -- -39% -61% s_sprintf 7805896/s 65% -- -36% sprintf 12216419/s 158% 57% -- Rate y_sprintf s_sprintf sprintf y_sprintf 4921710/s -- -31% -62% s_sprintf 7171893/s 46% -- -45% sprintf 12952997/s 163% 81% -- Rate y_sprintf s_sprintf sprintf y_sprintf 5370220/s -- -26% -62% s_sprintf 7269597/s 35% -- -49% sprintf 14253514/s 165% 96% -- Rate y_sprintf s_sprintf sprintf y_sprintf 4708990/s -- -33% -63% s_sprintf 6986810/s 48% -- -45% sprintf 12723873/s 170% 82% -- [download]	[reply] [d/l] [select]


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