intersection of scalar with 1D array and 2D array Matlab=>Perl

f77coder has asked for the wisdom of the Perl Monks concerning the following question:

Hello,

I'm converting some Matlab code into perl. Here's the Matlab code.

while ~feof(fileIDS);
  m1=fgetl(fileIDS);
  [a,b]=intersect(dataD{1},{deblank(m1)});
  if     (~isempty( a))
    data=dataD{2}(b);
  elseif(~isempty(intersect(dataT{1},{deblank(m1)})) )
    data=1.0;
  else
    data=0.0;
  end;
end;
[download]

dataD is a 2D array, dataT is a 1D array

m is a scalar value read from a file

a=returns index if there is one and null if it doesn't and b=value at index a

Basically what this does is the following

  intersection (2D data,scalar)
  if intersection exists not null
     a=index of location
     data= value of location at b
  elseif intersection (1D data,scalar) 
     data=1.0
  else
     data=0.0
  endif
[download]

I'm reading through this http://perldoc.perl.org/perlfaq4.html#How-do-I-test-whether-two-arrays-or-hashes-are-equal%3f but this assumes that the arrays are of equal dimensions (1D).

I'd like to know what is the simplest and fastest way?

use 5.12.0;
use strict;
use warnings;
use diagnostics;
use List::MoreUtils;

open my $TEST, '<', $f_Test or die "Could not open=> $f_Test : $!";
my $data;
while (my $scalar=<$TEST>)
{
  chomp($scalar);
[my $a, my $b]=firstidx { $_ == $scalar } @arrayPFA;
  if(!exists $a)
  {
    $data=$arrayPFA[$b];
  }
  elsif(if any { ! defined($scalar) } @arrayT;)
  {
    $data=1.0;
  }
  else
  {
    $data=0.0;
  };
};
close $TEST
[download]

Thanks for any help.

Comment on intersection of scalar with 1D array and 2D array Matlab=>Perl Select or Download Code

Replies are listed 'Best First'.
Re: intersection of scalar with 1D array and 2D array Matlab=>Perl by zentara (Archbishop) on Aug 30, 2014 at 08:44 UTC
I might add that PDL might be the most flexible solution. It's piddles can handle matrix manipulation fast and with some cool tricks too, that you might never expect. It seems to me you are looking to solve the problem of how to find the intersection of a vector and a planar surface. If I were you, I would ask this on the very friendly and helpful PDL maillist. The geniuses there ( not including me :-) ) have learned the tricks of piddle fu, and may just know the perfect piddle you need to be the fastest and most efficient. Which is the name of the game of course. :-) PS: PDL was designed in Fortran, which I assume, from your name, interests you f77coder I'm not really a human, but I play one on earth. Old Perl Programmer Haiku ................... flash japh	[reply]
Re^2: intersection of scalar with 1D array and 2D array Matlab=>Perl by f77coder (Beadle) on Aug 30, 2014 at 17:41 UTC
Thanks, this looks very promising. And yes I do prefer direct matrix manipulation versus associative arrays.	[reply]
Re^2: intersection of scalar with 1D array and 2D array Matlab=>Perl by f77coder (Beadle) on Aug 31, 2014 at 00:29 UTC
Where did the OSX binary go? It no longer on Sourceforge. `http://sourceforge.net/projects/pdl/files/` PDL is an interesting build on 10.8. Some difficult dependencies to resolve and it only likes gfortran-4.10 which I had to build. Sometimes it finds the compiler F77 for dependencies sometimes it doesn't.	[reply] [d/l]
Re^3: intersection of scalar with 1D array and 2D array Matlab=>Perl by etj (Deacon) on May 20, 2022 at 14:59 UTC
My recommendation for current MacOS: use Homebrew to install Perl, then install local::lib, then use Homebrew to install gfortran and other optional dependencies to get more of the optional stuff in PDL working, then use `cpanm PDL`. Ideally we'd have an up-to-date PDL packaged for MacOS, but that isn't currently the case.	[reply]
Re^3: intersection of scalar with 1D array and 2D array Matlab=>Perl by zentara (Archbishop) on Aug 31, 2014 at 09:06 UTC
They discuss good stuff like that on the PDL maillist. I'm not really a human, but I play one on earth. Old Perl Programmer Haiku ................... flash japh	[reply]
Re^2: intersection of scalar with 1D array and 2D array Matlab=>Perl by etj (Deacon) on May 20, 2022 at 14:56 UTC
PDL was designed in Fortran I don't think this is true? It started as an XS library (so a sort of C) for Perl (see PDL::Philosophy). But it does have bindings to various Fortran libraries: LAPACK (PDL::LinearAlgebra), Minuit 1 (PDL::Minuit), Slatec (PDL::Slatec), a non-linear optimisation library (PDL::Opt::NonLinear), and probably more.	[reply]
Re: intersection of scalar with 1D array and 2D array Matlab=>Perl by NetWallah (Canon) on Aug 30, 2014 at 04:07 UTC
A few modules that are likely to do the job well: List::Compare Quantum::Superpositions (if you like eigen states) Set::Array Other than that, some perlish syntax correction (NO logic correction) to your code: `while ( defined (my $scalar=<$TEST>) ) # This will accommodate the cas +e when $seclar is Zero { chomp($scalar); my ( $a, $b ) =firstidx { $_ == $scalar } @arrayPFA; # $a and $b ar +e NOT good names - they have special meanings in perl if(!defined $a) { $data=$arrayPFA[$b]; } elsif(if any { ! defined($scalar) } @arrayT;) # No idea what is inte +nded here... { $data=1.0; } else { $data=0.0; }; };` [download] "You're only given one little spark of madness. You mustn't lose it." - Robin Williams	[reply] [d/l]
Re^2: intersection of scalar with 1D array and 2D array Matlab=>Perl by choroba (Cardinal) on Aug 30, 2014 at 07:45 UTC
This will accommodate the case when $seclar is Zero Not needed: `$ perl -MO=Deparse -e 'while (my $scalar = <$TEST>) {1}' while (defined(my $scalar = <$TEST>)) { do { '???' }; } -e syntax OK` [download] Relevant: To Kill a Meme: while(defined($line = <>)) لսႽ� ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^3: intersection of scalar with 1D array and 2D array Matlab=>Perl by NetWallah (Canon) on Aug 31, 2014 at 01:20 UTC
Correct, scary, and certainly not obvious. Thanks for the education. More discussion on this issue is at stack overflow. "You're only given one little spark of madness. You mustn't lose it." - Robin Williams	[reply]
Re^2: intersection of scalar with 1D array and 2D array Matlab=>Perl by f77coder (Beadle) on Aug 30, 2014 at 04:28 UTC
Thanks for suggestion. I tried List::Compare and most of the flavors but they all bomb because I'm comparing a scalar to an array. All want 1D arrays to compare. I'll have a look at the others.	[reply]


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