Re^2: Searching parallel arrays.

And some (mediocre :-) code:

#!/usr/bin/perl -w
use strict;

my @source_data = (
    [ 100, 204, 312 ],
    [ 102, 313, 409 ],
    [ 205, 206, 315 ],
    [ 207, 210, 314 ],
);

my @sorted_numbers = sort map { @{$_} } @source_data;

# Using hash for the lookup. If your N numbers are fairly dense over
# 0..N then use an array for reduced mem consumption
my %from_whence;
foreach my $source_array (@source_data) {
    my $index = 0;
    foreach my $number (@$source_array) {
        $from_whence{$number} = [$source_array, $index];
        ++$index;
    }
};

# Look for 4 contig values
my @recent;
foreach my $number (@sorted_numbers) {
    push @recent, [ $number, $from_whence{$number} ];
    next unless scalar @recent > 4;
    shift @recent;
    check_and_handle_contig(\@recent);
}

exit 0;

sub check_and_handle_contig {
    my $numbers_info = shift;
    my $lastnum = undef;
    foreach my $numinfo (@$numbers_info) {
        my $num = $numinfo->[0];
        if ($lastnum) {
            return unless $num == $lastnum + 1;
        }
        $lastnum = $num;
    }

    print "Found sequence:\n";
    foreach my $numinfo (@$numbers_info) {
        my $num = $numinfo->[0];
        my $info = $numinfo->[1];
        print "$num from $info->[0]:$info->[1]\n";
    }
}
[download]

which prints:

Found sequence:
204 from ARRAY(0x814bc28):1
205 from ARRAY(0x8188e94):0
206 from ARRAY(0x8188e94):1
207 from ARRAY(0x8188ed0):0
Found sequence:
312 from ARRAY(0x814bc28):2
313 from ARRAY(0x8188c30):1
314 from ARRAY(0x8188ed0):2
315 from ARRAY(0x8188e94):2
[download]

Update: Limbic~Region++ noted that the sort in the above (more mediocre than I thought :-) code should be numeric, rather than the default sort. Update 2:And there's another bug, found by Not_a_Number, fixes below.

Comment on Re^2: Searching parallel arrays. Select or Download Code

Replies are listed 'Best First'.
Re^3: Searching parallel arrays. by Not_a_Number (Prior) on Dec 08, 2006 at 16:19 UTC
Not sure why, but I get no output from your code when I use these test data: `my @source_data = ( [ 1, 9, 17 ], [ 2, 10, 18 ], [ 3, 11, 19 ], [ 4, 12, 20 ], );` [download]	[reply] [d/l]
Re^4: Searching parallel arrays. by jbert (Priest) on Dec 08, 2006 at 16:35 UTC
Thanks. Looks like there are two bugs. The '1, 2, 3, 4' is being missed because the test in the loop is incorrect (due to my trying to avoid writing the test twice). The loop should be: `foreach my $number (@sorted_numbers) { push @recent, [ $number, $from_whence{$number} ]; shift @recent if @recent > 4; check_and_handle_contig(\@recent) if @recent == 4; }` [download] the other sequences are missed because of the numeric sort problem L~R noticed. The sort should be: `my @sorted_numbers = sort { $a <=> $b } map { @{$_} } @source_data;` [download] with these changes in, it seems to find them all. Thanks for the test cases :-)	[reply] [d/l] [select]