Beefy Boxes and Bandwidth Generously Provided by pair Networks
Think about Loose Coupling
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??

Here is last (hopefully) instalment in this thread; it only concerns faster, compared to the PDL CPAN tutorial, "Game of Life" implementation. But maybe some features used are too advanced for a tutorial. Improvement comes from:

  • To achieve wrap around, the ugly glueing in parent node is replaced with dicing along each axis. Very convenient function.
  • Horrible expression to compute next generation (requires 8 operations on whole arrays) is replaced with shorter version (just 4).
use strict; use warnings; use feature 'say'; use Time::HiRes 'time'; use PDL; use PDL::NiceSlice; use Test::PDL 'eq_pdl'; use constant { WIDTH => 20, HEIGHT => 20, STEPS => 1000, }; my $x = zeroes long, WIDTH, HEIGHT; # Put in a simple glider. $x(1:3,1:3) .= pdl ( [1,1,1], [0,0,1], [0,1,0] ); my $backup = $x-> copy; printf "Game of Life!\nMatrix: %s, %d generations\n", $x-> info, STEPS; # Tutorial my $t = time; for ( 1 .. STEPS ) { my $t_ = time; # Calculate the number of neighbours per cell. my $n = $x->range(ndcoords($x)-1,3,"periodic")->reorder(2,3,0,1); $n = $n->sumover->sumover - $x; # Calculate the next generation. $x = ((($n == 2) + ($n == 3))* $x) + (($n == 3) * !$x); } printf "Tutorial: %0.3f s\n", time - $t; # Faster my $m = $backup-> copy; $t = time; my $wrap_w = pdl [ reverse WIDTH - 1, ( 0 .. WIDTH - 1 ), 0 ]; my $wrap_h = pdl [ reverse HEIGHT - 1, ( 0 .. HEIGHT - 1 ), 0 ]; for ( 1 .. STEPS ) { my $n = $m -> dice_axis( 0, $wrap_w ) -> lags( 0, 1, WIDTH ) -> sumover -> dice_axis( 1, $wrap_h ) -> lags( 1, 1, HEIGHT ) -> xchg( 0, 1 ) -> sumover; $n -= $m; $m = ( $n == 3 ) | $m & ( $n == 2 ) } printf "Faster: %0.3f s\n", time - $t; die unless eq_pdl( $x, $m ); __END__ Game of Life! Matrix: PDL: Long D [20,20], 1000 generations Tutorial: 0.341 s Faster: 0.111 s Matrix: PDL: Long D [200,200], 100 generations Tutorial: 0.845 s Faster: 0.086 s Matrix: PDL: Long D [1000,1000], 20 generations Tutorial: 4.422 s Faster: 0.443 s Matrix: PDL: Long D [2000,2000], 10 generations Tutorial: 8.878 s Faster: 0.872 s

In reply to Re^3: Fast sliding submatrix sums with PDL (inspired by PWC 248 task 2) by Anonymous Monk
in thread Fast sliding submatrix sums with PDL (inspired by PWC 248 task 2) by Anonymous Monk

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?Last hourOther CB clients
Other Users?
Others about the Monastery: (3)
As of 2024-06-25 02:17 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found

    Notices?
    erzuuli‥ 🛈The London Perl and Raku Workshop takes place on 26th Oct 2024. If your company depends on Perl, please consider sponsoring and/or attending.