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Contents
module Bmg
module Operator
#
# Summarize operator.
#
# Makes a summarization by some attributes, applying aggregations
# to the corresponding images.
#
class Summarize
include Operator::Unary
def initialize(type, operand, by, summarization)
@type = type
@operand = operand
@by = by
@summarization = Summarizer.summarization(summarization)
end
protected
attr_reader :by, :summarization
public
def each
return to_enum unless block_given?
# summary key => summarization memo, starting with least
result = Hash.new{|h,k|
h[k] = Hash[@summarization.map{|k,v|
[ k, v.least ]
}]
}
# iterate each tuple
@operand.each do |tuple|
key = TupleAlgebra.project(tuple, @by)
# apply them all and create a new memo
result[key] = Hash[@summarization.map{|k,v|
[ k, v.happens(result[key][k], tuple) ]
}]
end
# Merge result keys and values
result.each_pair do |by,sums|
tuple = Hash[@summarization.map{|k,v|
[ k, v.finalize(sums[k]) ]
}].merge(by)
yield(tuple)
end
end
def to_ast
[ :summarize, operand.to_ast, by, summarization ]
end
protected ### inspect
def args
[ by, summarization ]
end
end # class Summarize
end # module Operator
end # module Bmg
Version data entries
28 entries across 28 versions & 1 rubygems