in reply to Re^3: Create unique array --the hard way!
in thread Create unique array --the hard way!
Well, you could but I don't know why you'd want to.
In the following script (using Benchmark) you'll see:
- splice is relatively less efficient. I also suspect it might have future maintainers scratching their heads wondering why it was used ("splice @array, 0, 1" has identical functionality to "shift @array" — it's just slower and requires more keystrokes to code).
- shift is more efficient than splice.
- My original map is faster than both of those; it doesn't destroy the original array; and it's a lot less coding.
#!/usr/bin/env perl use strict; use warnings; use Benchmark qw{cmpthese}; cmpthese -1 => { splice_unique => \&splice_unique, shift_unique => \&shift_unique, map_unique => \&map_unique, }; sub splice_unique { my @sorted = sort qw{q w e r t y q w e r t y}; my $last = ''; my @unique; while (@sorted) { my $element = splice @sorted, 0, 1; if ($last ne $element) { $last = $element; push @unique, $element } } } sub shift_unique { my @sorted = sort qw{q w e r t y q w e r t y}; my $last = ''; my @unique; while (@sorted) { my $element = shift @sorted; if ($last ne $element) { $last = $element; push @unique, $element } } } sub map_unique { my @sorted = sort qw{q w e r t y q w e r t y}; my $last = ''; my @unique = map { $last eq $_ ? () : ($last = $_) } @sorted; }
Representative result:
Rate splice_unique shift_unique map_unique splice_unique 93699/s -- -5% -20% shift_unique 98642/s 5% -- -16% map_unique 117028/s 25% 19% --
-- Ken
In Section
Seekers of Perl Wisdom