Re^3: Sorting a hash of arrays based on a particular array element.

Oh silly silly me ... 2 million values thrown into a hash with only 100 possible keys !!!

# for (1..$elements) {
#    my ($key, $one, $two) = rand =~/(\d\.\d{2})(\d{2})(\d{4})/;
#   $hash{$key} = [$one, $two];
#}

for (1..$elements) {
    my ($one, $two) = rand =~/\d+.(\d{6})(\d{4})/;
    $hash{$_} = [$one, $two];
}

# Also reduced $elements to 200_000 and 2 million 
# exceeded per proc memeory limit.

# I also use more entropy in the field to sort on 
# requiring a change of packed_default to ...

sub packed_default {
    my @sorted_keys =
        map substr($_,4),
        sort map {pack('N', $hash{$_}[0])."$_"}
        keys %hash;
    return @sorted_keys;
}

Benchmark: timing 10 iterations of BroweserUK, packed_default...
BroweserUK: 188 wallclock secs 
    (175.63 usr +  0.13 sys = 175.76 CPU) @  0.06/s (n=10)
packed_default: 72 wallclock secs 
    (64.61 usr +  0.16 sys = 64.77 CPU) @  0.15/s (n=10)
[download]

Sadly I am on a company machine with a restrictive policy about installing modules so I can not test Sort::Key here, will give it a bash at home this evening.

Cheers,
R.

Pereant, qui ante nos nostra dixerunt!

Comment on Re^3: Sorting a hash of arrays based on a particular array element. Download Code

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Re^4: Sorting a hash of arrays based on a particular array element. by salva (Canon) on Jul 28, 2005 at 13:57 UTC
on my computer (for 1M elements): `s/iter BrowserUK packed_default SortKey BrowserUK 71.7 -- -66% -79% packed_default 24.5 193% -- -38% SortKey 15.2 372% 61% --` [download] another important point for sorting algorithms is their memory comsumption, and the GRT offers the worst behaviour for that aspect: `use Memchmark qw(cmpthese); ... cmpthese(BrowserUK => \&BrowserUK, packed_default => \&packed_default, SortKey => \&SortKey ); __end__ test: BrowserUK, memory used: 102006784 bytes test: SortKey, memory used: 85598208 bytes test: packed_default, memory used: 182788096 bytes` [download] (Memchmark results are approximate, but accurate enough to show the difference)	[reply] [d/l] [select]

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Re^4: Sorting a hash of arrays based on a particular array element.
by salva (Canon) on Jul 28, 2005 at 13:57 UTC

               s/iter      BrowserUK packed_default        SortKey
BrowserUK        71.7             --           -66%           -79%
packed_default   24.5           193%             --           -38%
SortKey          15.2           372%            61%             --
[download]

use Memchmark qw(cmpthese);

...

cmpthese(BrowserUK => \&BrowserUK,
     packed_default => \&packed_default,
     SortKey => \&SortKey );
__end__

test: BrowserUK, memory used: 102006784 bytes
test: SortKey, memory used: 85598208 bytes
test: packed_default, memory used: 182788096 bytes
[download]

Memchmark

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