Re^3: Splitting array into two with a regex

To generalize it even further:

sub partition (&$@)
{
    my $condition = shift;
    my $receivers_ar = shift;
    push @{ $receivers_ar->[ &$condition ] }, $_ for @_;
    @$receivers_ar
}

# Example 1:

my( @good, @bad );
partition { /u/ ? 1 : 0 } [ \@good, \@bad ], qw( foo bar quux );

print "good=@good\n";
print "bad=@bad\n";

# Example 2:

my @r = partition { $_ % 3 } [ [], [], [], ], 0 .. 12;

for my $i ( 0 .. $#r )
{
    print "$i = @{$r[$i]}\n";
}
[download]

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Comment on Re^3: Splitting array into two with a regex Download Code

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Re^4: Splitting array into two with a regex by dragonchild (Archbishop) on Nov 08, 2005 at 17:58 UTC
Since we're using prototypes, another way might look like: `sub partition (&\@\@\@) { my ($cond, $start, $true, $false) = @_; for (@$start) { push @{ $cond->() ? $true : $false }, $_; } return; } my @arr = 1 .. 9; my (@greater, @less); partition { $_ > 5 } @arr => @greater, @less; print "@greater\n@less\n";` [download] My criteria for good software: Does it work? Can someone else come in, make a change, and be reasonably certain no bugs were introduced?	[reply] [d/l]
Re^4: Splitting array into two with a regex by Roy Johnson (Monsignor) on Nov 08, 2005 at 16:33 UTC
Nice. Note that Example 2 can be called as such: `my @r = partition { $_ % 3 } [], 0 .. 12;` [download] and autovivification will create the sub-refs, though only for those elements that actually get assigned to. It's probably best to go ahead and specify the arrayrefs, but it could be a little cumbersome. It can be made simpler by a little tweak: the 2nd argument can be an arrayref or a number; if a number, `partition` creates that many sub-array(ref)s. `sub partition (&$@) { my $condition = shift; my $receivers_ar = shift; ref $receivers_ar or $receivers_ar = [ map [], 1..$receivers_ar ]; push @{ $receivers_ar->[ &$condition ] }, $_ for @_; @$receivers_ar } my @r = partition { $_ % 3 } 3, 0 .. 12;` [download] Also note that the `map` cannot be replaced with `([]) x $receivers_ar` because that will make three copies of the same ref. Caution: Contents may have been coded under pressure.	[reply] [d/l] [select]