File Coverage

blib/lib/Statistics/RatioVariance.pm

Criterion	Covered	Total	%
statement	1	3	33.3
branch			n/a
condition			n/a
subroutine	1	1	100.0
pod			n/a
total	2	4	50.0

package Statistics::RatioVariance;

use Statistics::Basic qw(:all);
use Statistics::Zed;

our $VERSION = '1.00';

sub calc{

    # This variables must be references to arrays.
    my($self, $xvector, $yvector, $xvariance, $yvariance) = @_;

    # Calculates ·
    my $kxvector    = 0;
    my $kyvector    = 0;
    my $kxvariance  = 0;
    my $kyvariance  = 0;

    #my $counter = 0;
    #print "X-Vector lenght: ".$#{$xvector}." - ".${$xvector}[0]."\n";
    #print "Y-Vector lenght: ".$#{$yvector}."\n";
    #print "X-Var lenght: ".$#{$xvariance}."\n";
    #print "Y-Var lenght: ".$#{$yvariance}."\n";

    for(my $i=0;$i<$#{$xvector};$i++){

            $kxvector   = $kxvector + ${$xvector}[$i] if ${$xvector}[$i] ;
            $kyvector   = $kyvector + ${$yvector}[$i] if ${$yvector}[$i] ;
            $kxvariance = $kxvariance + ${$xvariance}[$i] if ${$xvariance}[$i] ;
            $kyvariance = $kyvariance + ${$yvariance}[$i] if ${$yvariance}[$i] ;

            #print "$counter:kxvector: $kxvector\n";
            #print "$counter:kyvector: $kyvector\n";
            #print "$counter:kxvariance: $kxvariance\n";
            #print "$counter:kyvariance: $kyvariance\n";

            #$counter++;

    }

    # Calculates ^x and ^y (means)
    my $xmean = $kxvector;
    my $ymean = $kyvector;

    # Calculates correlation coefficent
    my $correlation = correlation($xvector, $yvector);

    # Calculates the cocient
    my $cocient = $xmean/$ymean;

    # Calculates the variance (STEP-BY-STEP)
    my $first_term = 1/($ymean*$ymean);

    my $second_term_first_term = $kxvariance;
    my $second_term_second_term = ($cocient*$cocient)*$kyvariance;
    my $second_term_third_term = 2*$cocient*$correlation*(sqrt($kxvariance))*(sqrt($kyvariance));
    my $second_term = $second_term_first_term + $second_term_second_term - $second_term_third_term;

    my $cocient_variance = $first_term*$second_term;

    # Wanna debug?
    #print "Correlation: $correlation\n";
    #print "First term: 1/$ymean $first_term\n";
    #print "Second term - First term: $second_term_first_term\n";
    #print "Second term - Second term: $second_term_second_term\n";
    #print "Second term - Third term: $second_term_third_term\n";
    #print "Second term: $second_term\n";
    #print "Cocient variance: $cocient_variance\n";

    # ..Fiu!

    # It seems a zero-value for variance is not allowed in function $zed->score
    #$cocient_variance == 0 ? $cocient_variance = 0.000001 : $cocient_variance;

    # Creates the ztest obj with default values (see perldoc Statistics::Zed to settings this values)
    my $zed = Statistics::Zed->new();
    my ($z_value, $p_value, $observed_deviation, $standar_deviation) = $zed->score(observed => $cocient, expected => 1, variance => $cocient_variance);

    # Create a hash for the returning value with all the calculated params
    my %hash = ();

    $hash{xsum}               = $kxvector;
    $hash{ysum}               = $kyvector;
    $hash{x_var_sum}          = $kxvariance;
    $hash{y_var_sum}          = $kyvariance;
    $hash{cocient}            = $cocient;
    $hash{correlation}        = $correlation;
    $hash{cocient_variance}   = $cocient_variance;
    $hash{z_value}            = $z_value;
    $hash{p_value}            = $p_value;
    $hash{observed_deviation} = $observed_deviation;
    $hash{standar_deviation}  = $standar_deviation;


    return %hash;

}

1;

__END__