Re: Fast Way to find one array in second array

Here’s a more Perlish version of your code, using Set::Tiny for the convenience of its is_subset method:

use strict;
use warnings;
use Set::Tiny 'set';
 
my @paths =
(
    [ qw(A B F G)       ],
    [ qw(A B)           ],
    [ qw(A B X)         ],
    [ qw(A B C D E F G) ],
    [ qw(I J K L M)     ],
);

my   @sets;
push @sets, set(@$_) for @paths;
     @sets = sort { $a->size <=> $b->size } @sets;    # UPDATED
my   @filtered;

LINE: for my $i (0 .. $#sets)
{
    my $set_i = $sets[$i];

    for my $j ($i + 1 .. $#sets)
    {
        next LINE if $set_i->is_subset($sets[$j]);
    }

    push @filtered, $set_i;
}

print $_->as_string, "\n" for @filtered;
[download]

<Update> Added sort line marked # UPDATED as per BrowserUk’s post below. </Update>

Now (other things being equal), the larger the set J, the more likely it is that J is a superset of a given set I. So an obvious speedup to try is to test I against the larger sets first, by reverseing the inner loop:

for my $j (reverse($i + 1 .. $#sets))
[download]

Of course, you’ll need to Benchmark the code to determine whether this makes a significant difference for your input data.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

Comment on Re: Fast Way to find one array in second array Select or Download Code

Replies are listed 'Best First'.

Re^2: Fast Way to find one array in second array
by BrowserUk (Patriarch) on Aug 14, 2016 at 16:50 UTC

That doesn't seem to produce the correct results. Given this input:

C:\test>1169736-st.pl
[
  ["S", "N", "H", "A", "C", "J", "D", "E", "Z", "L"],
  ["S", "Y", "Y", "O", "D", "M", "G", "W", "F", "U"],
  ["Z", "Z", "P", "K", "G", "H", "V", "A", "J", "C"],
  ["P", "E", "E", "V", "M", "E", "N", "T", "K", "H"],
  ["I", "L", "H", "Z", "H", "T", "O", "F", "T", "V"],
  ["I", "Y", "H", "I", "D", "T", "V", "S", "P"],
  ["G", "D", "A", "B", "U", "W", "F", "D", "O"],
  ["L", "J", "B", "P", "U", "U", "N", "H"],
  ["B", "A", "X", "H", "H", "P", "R", "V"],
  ["M", "F", "T", "M", "L", "Y", "T", "C"],
  ["L", "C", "Y", "X", "O", "I", "M", "J"],
  ["K", "T", "P", "O", "J", "D", "F"],
  ["R", "T", "S", "M", "D", "J", "V"],
  ["D", "Y", "D", "X", "S", "H"],
  ["N", "O", "P", "P", "E"],
  ["U", "N", "Z", "T", "I"],
  ["B", "Z", "R", "D", "W"],
  ["N", "X", "A", "Z", "O"],
  ["T", "R", "O", "B", "L"],
  ["X", "V", "T", "E"],
  ["V", "P", "M"],
  ["V", "Q", "R"],
  ["V", "D", "C"],
  ["S", "H", "L"],
  ["P", "N", "Q"],
  ["A", "A"],
  ["R", "M"],
  ["O"],
  ["S"],
  ["N"],
  ["N"],
  ["C"],
]
[download]

It produces:

[
  bless({ A => undef, C => undef, D => undef, E => undef, H => undef, 
+J => undef, L => undef, N => undef, S => undef, Z => undef }, "Set::T
+iny"),
  bless({ D => undef, F => undef, G => undef, M => undef, O => undef, 
+S => undef, U => undef, W => undef, Y => undef }, "Set::Tiny"),
  bless({ A => undef, C => undef, G => undef, H => undef, J => undef, 
+K => undef, P => undef, V => undef, Z => undef }, "Set::Tiny"),
  bless({ E => undef, H => undef, K => undef, M => undef, N => undef, 
+P => undef, T => undef, V => undef }, "Set::Tiny"),
  bless({ F => undef, H => undef, I => undef, L => undef, O => undef, 
+T => undef, V => undef, Z => undef }, "Set::Tiny"),
  bless({ D => undef, H => undef, I => undef, P => undef, S => undef, 
+T => undef, V => undef, Y => undef }, "Set::Tiny"),
  bless({ A => undef, B => undef, D => undef, F => undef, G => undef, 
+O => undef, U => undef, W => undef }, "Set::Tiny"),
  bless({ B => undef, H => undef, J => undef, L => undef, N => undef, 
+P => undef, U => undef }, "Set::Tiny"),
  bless({ A => undef, B => undef, H => undef, P => undef, R => undef, 
+V => undef, X => undef }, "Set::Tiny"),
  bless({ C => undef, F => undef, L => undef, M => undef, T => undef, 
+Y => undef }, "Set::Tiny"),
  bless({ C => undef, I => undef, J => undef, L => undef, M => undef, 
+O => undef, X => undef, Y => undef }, "Set::Tiny"),
  bless({ D => undef, F => undef, J => undef, K => undef, O => undef, 
+P => undef, T => undef }, "Set::Tiny"),
  bless({ D => undef, J => undef, M => undef, R => undef, S => undef, 
+T => undef, V => undef }, "Set::Tiny"),
  bless({ D => undef, H => undef, S => undef, X => undef, Y => undef }
+, "Set::Tiny"),
  bless({ E => undef, N => undef, O => undef, P => undef }, "Set::Tiny
+"),
  bless({ I => undef, N => undef, T => undef, U => undef, Z => undef }
+, "Set::Tiny"),
  bless({ B => undef, D => undef, R => undef, W => undef, Z => undef }
+, "Set::Tiny"),
  bless({ A => undef, N => undef, O => undef, X => undef, Z => undef }
+, "Set::Tiny"),
  bless({ B => undef, L => undef, O => undef, R => undef, T => undef }
+, "Set::Tiny"),
  bless({ E => undef, T => undef, V => undef, X => undef }, "Set::Tiny
+"),
  bless({ M => undef, P => undef, V => undef }, "Set::Tiny"),
  bless({ Q => undef, R => undef, V => undef }, "Set::Tiny"),
  bless({ C => undef, D => undef, V => undef }, "Set::Tiny"),
  bless({ H => undef, L => undef, S => undef }, "Set::Tiny"),
  bless({ N => undef, P => undef, Q => undef }, "Set::Tiny"),
  bless({ A => undef }, "Set::Tiny"),
  bless({ M => undef, R => undef }, "Set::Tiny"),
  bless({ O => undef }, "Set::Tiny"),
  bless({ S => undef }, "Set::Tiny"),
  bless({ N => undef }, "Set::Tiny"),
  bless({ C => undef }, "Set::Tiny"),
]
[download]

At least the last 6 subsets should not have made it into @filtered.

It should produce (+-the blessing):

[
  ["S", "N", "H", "A", "C", "J", "D", "E", "Z", "L"],
  ["S", "Y", "Y", "O", "D", "M", "G", "W", "F", "U"],
  ["Z", "Z", "P", "K", "G", "H", "V", "A", "J", "C"],
  ["P", "E", "E", "V", "M", "E", "N", "T", "K", "H"],
  ["I", "L", "H", "Z", "H", "T", "O", "F", "T", "V"],
  ["I", "Y", "H", "I", "D", "T", "V", "S", "P"],
  ["G", "D", "A", "B", "U", "W", "F", "D", "O"],
  ["L", "J", "B", "P", "U", "U", "N", "H"],
  ["B", "A", "X", "H", "H", "P", "R", "V"],
  ["M", "F", "T", "M", "L", "Y", "T", "C"],
  ["L", "C", "Y", "X", "O", "I", "M", "J"],
  ["K", "T", "P", "O", "J", "D", "F"],
  ["R", "T", "S", "M", "D", "J", "V"],
  ["D", "Y", "D", "X", "S", "H"],
  ["N", "O", "P", "P", "E"],
  ["U", "N", "Z", "T", "I"],
  ["B", "Z", "R", "D", "W"],
  ["N", "X", "A", "Z", "O"],
  ["T", "R", "O", "B", "L"],
  ["X", "V", "T", "E"],
  ["V", "Q", "R"],
  ["V", "D", "C"],
  ["P", "N", "Q"],
]
[download]

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority". I knew I was on the right track :)

In the absence of evidence, opinion is indistinguishable from prejudice.

[reply]
[d/l]
[select]

Re^3: Fast Way to find one array in second array

by Athanasius (Archbishop) on Aug 15, 2016 at 06:20 UTC

You’re right, thanks! I forgot to include the OP’s code for sorting the path arrays according to number of elements. Node updated:

...
     @paths = sort { @$a <=> @$b } @paths;
my   @sets;
push @sets, set(@$_) for @paths;
my   @filtered;
...
[download]

Now the output for your input data is as follows:


Problems? Is your data what you think it is?
	PerlMonks