Beefy Boxes and Bandwidth Generously Provided by pair Networks
Syntactic Confectionery Delight
 
PerlMonks  

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??
Here's a version that only requires a single pass over the array. The end result is that the 5th element of each segment is a ref to the next one. The last one doesn't reference the next or we'd get a circular structure.
use warnings; use strict; my @seg = ( [ 1, 1, 2, 1 ], [ 5, 5, 1, 5 ], [ 2, 3, 5, 3 ], [ 5, 3, 5, 5 ], [ 2, 1, 2, 3 ], [ 1, 5, 1, 1 ] ); use Data::Dumper qw(Dumper); my (%have, %want); while (my $seg = shift @seg) { my $have = join(",", @{$seg}[0,1]); my $want = join(",", @{$seg}[2,3]); print "we have $have\n"; if (my $wanted = delete $want{$have}) { print "something wants it\n"; $wanted->[4] = $seg; } else { print "nothing wants it yet\n"; $have{$have} = $seg; } last if @seg == 0; # don't want to make a circular reference print "we want $want\n"; if (my $had = delete $have{$want}) { print "found it\n"; $seg->[4] = $had; } else { print "didn't find it, asking for it\n"; $want{$want} = $seg; } } $Data::Dumper::Indent = 0; print Dumper values %have;
the end result is
[1,1,2,1,[2,1,2,3,[2,3,5,3,[5,3,5,5,[5,5,1,5,[1,5,1,1]]]]]]
It's glorious day in Dublin so I'm off to the pub now :-)

UpdateI suppose it does require a second pass to produce output in the format requested...


In reply to Re: reordering segments to form a polygon by fergal
in thread reordering segments to form a polygon by dada

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others scrutinizing the Monastery: (1)
As of 2022-11-26 11:46 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?
    Notices?