Sha256: a9afcd262fe39ccdf7f11a9920a139c3dad6af4206693649cf2f62c89044fdaa
Contents?: true
Size: 1.85 KB
Versions: 21
Compression:
Stored size: 1.85 KB
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 = Summarize.compile(summarization)
end
protected
attr_reader :by, :summarization
public
def each
# 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
private
# Compile a summarization hash so that every value is a Summarizer
# instance
def self.compile(summarization)
Hash[summarization.map{|k,v|
summarizer = case v
when Summarizer then v
when Symbol then Summarizer.send(v, k)
else
raise ArgumentError, "Unexpected summarizer #{k} => #{v}"
end
[ k, summarizer ]
}]
end
end # class Summarize
end # module Operator
end # module Bmg
Version data entries
21 entries across 21 versions & 1 rubygems