Returning Statistics::LineFit variables from a sub

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

Dear Monks,

I'm having difficulty working out how to return the variables a, b and R2 from the subroutines as three separate variables.


  my $lfit = Statistics::LineFit->new();
  $lfit->setData($x_ref, $y_ref);
  
  printf "a=%.4f, b=%.4f,  R2=%.4f\n", $lfit->coefficients(), $lfit->r
+Squared();
  

  return  "a=%.4f, b=%.4f,  R2=%.4f\n", $lfit->coefficients(), $lfit->
+rSquared();

}
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Re: Returning Statistics::LineFit variables from a sub by grinder (Bishop) on Nov 22, 2007 at 17:33 UTC
Your code, as posted, works just fine for me. If you want, you could list assign the results from the `coefficients` method. Might make things a bit more self-documenting: `use strict; use warnings; use Statistics::LineFit; my $fit = Statistics::LineFit->new; $fit->setData( [qw[ 1 2 3 4 5 6 7]], [qw[ 2 3 4 5.5 6.5 7.5 8.5]], ) or die; my ($intercept, $slope) = $fit->coefficients; printf "i=%.4f, s=%.4f, R2=%.4f\n", $intercept, $slope, $fit->rSquare +d; # or return ($fit->coefficients, $fit->rSquared);` [download] Maybe you're calling your function that does this stuff in scalar context, and thus flattening the return list? What exactly are you getting back? • another intruder with the mooring in the heart of the Perl	[reply] [d/l]
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Re: Returning Statistics::LineFit variables from a sub by andreas1234567 (Vicar) on Nov 22, 2007 at 17:44 UTC
I would use a hash reference. See perldata and perlref. Are you still struggling with LineFit.pm error due to undef value? use strict; use warnings; use Statistics::LineFit; use Data::Dumper; sub get_hashref { my ($x_ref, $y_ref) = ([1,2,3], [4,5,6]); my $lfit = Statistics::LineFit->new(); $lfit->setData($x_ref, $y_ref); my ($intercept, $slope) = $lfit->coefficients(); my $rSquared = $lfit->rSquared(); my $hashref = { a => $intercept, b => $slope, c => $rSquared }; return $hashref; } # ------ main ------ my $hr = get_hashref(); print Dumper($hr); __END__ $ perl -l 652420.pl $VAR1 = { 'c' => '1', 'a' => '3', 'b' => 1 }; [download] -- Andreas	[reply] [d/l]