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Contents
module SPARQL; module Algebra
class Operator
##
# The SPARQL `avg` set function.
#
# @example
# (prefix ((: <http://www.example.org/>))
# (project (?avg)
# (extend ((?avg ?.0))
# (group () ((?.0 (avg ?o)))
# (bgp (triple ?s :dec ?o))))))
#
# @see http://www.w3.org/TR/sparql11-query/#defn_aggAvg
class Avg < Operator::Unary
include Aggregate
NAME = :avg
##
# The Avg set function calculates the average value for an expression over a group. It is defined in terms of Sum and Count.
#
# @param [Enumerable<Array<RDF::Term>>] enum
# enum of evaluated operand
# @return [RDF::Literal::Numeric] The numeric average of the terms
def apply(enum)
if enum.empty?
RDF::Literal(0)
elsif enum.flatten.all? {|n| n.is_a?(RDF::Literal::Numeric)}
enum.flatten.reduce(:+) / RDF::Literal::Decimal.new(enum.length)
else
raise TypeError, "Averaging non-numeric types: #{enum.flatten}"
end
end
end # Avg
end # Operator
end; end # SPARQL::Algebra
Version data entries
25 entries across 25 versions & 1 rubygems