Statistics::Basic::ComUserdContributed PerStatistics::Basic::ComputedVector(3)NAMEStatistics::Basic::ComputedVector - a class for computing filtered
vectors
SYNOPSIS
Invoke it this way:
my $vector = vector(1,2,3);
my $computed = computed($vector)->set_filter(sub{
# NOTE: only interested in even numbers:
grep { !($_ % 2) } @_
});
# nearly the same, opposite order:
my $computed = computed(1,2,3)->set_filter(sub {map{$_+1}@_});
my $vector = $computed->query_vector;
METHODSnew()
The constructor takes a single array ref or a single
Statistics::Basic::ComputedVector as its argument. It returns a
Statistics::Basic::ComputedVector object.
If passed arguments other than Statistics::Basic::Vector objects,
the constructor will built an appropriate vector object -- which
can be queried with "query_vector()"
Note: normally you'd use the computed() constructor, rather than
building these by hand using "new()".
copy()
Creates a new computed vector object referring to the same source
vector and using the same filter as this one.
my $v1 = vector(1,2,3);
my $c1 = computed($v1); $c1->set_filter(my $s = sub {});
my $copy1 = computed($v1); $copy1->set_filter($s);
my $copy2 = $c1->copy; # just like $c2, but in one step
To instead create a filtered version of a filtered vector, choose
this form:
my $v1 = vector(1,2,3);
my $c1 = computed($v1); $c1->set_filter(sub {});
my $c2 = computed($c1); $c2->set_filter(sub {});
insert()
Insert new values into the input vector. If the vector was already
full (see "set_size()"), this will also shift oldest elements from
the input vector to compensate.
$computed->insert( 4, 3 ); # insert a 3 and a 4
Note that continuing from the "SYNOPSIS" example, this would
certainly insert a 4 and a 3 into the input vector, but the 3
wouldn't be returned from a "query()" because it is odd.
This function returns the object itself, for chaining purposes.
append()ginsert()
Insert new values into the input vector. If the vector was already
full (see "set_size()"), these functions will grow the size of the
input vector to accommodate the new values, rather than shifting
things.
$computed->append( 4, 3 ); # append a 3 and a 4
Note that continuing from the "SYNOPSIS" example, this would
certainly insert a 4 and a 3 into the input vector, but the 3
wouldn't be returned from a "query()" because it is odd.
This function returns the object itself, for chaining purposes.
query()
"query()" returns the contents of the computed vector (after
filtering) either as a list or as an arrayref.
my @copy_of_contents = $computed->query;
my $reference_to_contents = $computed->query;
Note that changing the $reference_to_contents will not usefully
affect the contents of the vector itself, but it will adversely
affect any computations based on the vector. If you need to change
the contents of a vector in a special way, use another
Statistics::Basic::ComputedVector object instead.
Keeping $reference_to_contents available long term should work
acceptably (since it refers to the vector contents itself).
query_vector()
Return the input Statistics::Basic::Vector object.
query_filled()
This returns true when the input vector is full (see
"query_filled()" in Statistics::Basic::Vector). This is of
questionable usefulness on computed vectors, but is provided for
completeness (and internal package consistency).
query_size()
Return the current size of the computed vector.
set_filter()
Set the filtering for the computed vector. This function takes a
single coderef argument -- all other arguments will be ignored.
The elements of the input vector are passed to your filter coderef
in @_ and your ref should return the calculated elements of the
computed vector as a list.
my $vec = vector(1,2,3);
my $pow = computed($vec);
$pow->set_filter(sub { return map { $_ ** 2 } @_ })
If you need to call more than one filter function, concatenate them
together using map or an anonymous sub.
$pow->set_filter(sub { return f1(f2(f3(f4(@_)))) });
This function returns the object itself, for chaining purposes.
set_size()
Set the size of the input vector (not the computed vector, that
would make little sense).
This function returns the object itself, for chaining purposes.
set_vector()
Set the contents of the input vector (not the computed one).
This function returns the object itself, for chaining purposes.
OVERLOADS
This object is overloaded. It tries to return an appropriate string
for the vector and raises errors 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::Vector
perl v5.14.12009-06-Statistics::Basic::ComputedVector(3)
