Statistics::Basic::CovUsernContributed Perl DoStatistics::Basic::Covariance(3)NAMEStatistics::Basic::Covariance - find the covariance between two lists
SYNOPSIS
Invoke it this way:
my $covariance = covariance( [1,2,3], [1,2,3] );
Or this way:
my $v1 = vector(1,2,3);
my $v2 = vector(1,2,3);
my $cov = cov($v1,$v2);
And then either query the values or print them like so:
print "The covariance between $v1 and $v2: $covariance\n";
my $cq = $cov->query;
my $c0 = 0+$cov;
Create a 20 point "moving" covariance like so:
use Statistics::Basic qw(:all nofill);
my $sth = $dbh->prepare("select col1,col2 from data where something");
my $len = 20;
my $cov = cov();
$cov->set_size($len);
$sth->execute or die $dbh->errstr;
$sth->bind_columns( my ($lhs, $rhs) ) or die $dbh->errstr;
my $count = $len;
while( $sth->fetch ) {
$cov->insert( $lhs, $rhs );
if( defined( my $c = $cov->query ) ) {
print "Covariance: $c\n";
}
# This would also work:
# print "Covariance: $cov\n" if $cov->query_filled;
}
METHODS
This list of methods skips the methods inherited from
Statistics::Basic::_TwoVectorBase (things like query(), insert(), and
ginsert()).
new()
Create a new Statistics::Basic::Covariance object. This function
takes two arguments -- which can either be arrayrefs or
Statistics::Basic::Vector objects. This function is called when
the covariance() shortcut-function is called.
query_vector1()
Return the Statistics::Basic::Vector for the first vector.
query_vector2()
Return the Statistics::Basic::Vector object for the second vector.
query_mean1()
Returns the Statistics::Basic::Mean object for the first vector.
query_mean2()
Returns the Statistics::Basic::Mean object for the second vector.
OVERLOADS
This object is overloaded. It tries to return an appropriate string
for the calculation or the value of the computation in numeric context.
In boolean context, this object is always true (even when empty).
AUTHOR
Paul Miller "<jettero@cpan.org>"
COPYRIGHT
Copyright 2009 Paul Miller -- Licensed under the LGPL
SEE ALSOperl(1), Statistics::Basic, Statistics::Basic::_TwoVectorBase,
Statistics::Basic::Vector
perl v5.14.1 2009-06-28 Statistics::Basic::Covariance(3)
