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Contents
require_relative("group")
module Wukong
class Processor
class Moments < Group
field :group_by, Whatever, :doc => "Part of the record to group by"
attr_accessor :measurements
field :of, Array, :default => [], :doc => "Parts of the record to measure moments of"
field :no_std_dev, :boolean, :doc => "Don't compute standard deviations"
def get_key record
super(record) unless (self.group_by || self.by)
get(self.group_by || self.by, record)
end
def receive_of o
@of = case o
when String then o.split(',')
when Array then o
else []
end
end
def start record
super(record)
@measurements = {}.tap do |m|
self.of.each do |property|
m[property] = []
end
end
end
def accumulate record
super(record)
self.of.each do |property|
if raw = get(property, record)
self.measurements[property] << (raw.to_f rescue next)
end
end
end
def results
{}.tap do |r|
measurements.each_pair do |property, values|
r[property] = {}
next if values.empty?
count = values.size.to_f
r[property][:count] = count.to_i
mean = values.inject(0.0) { |sum, value| sum += value } / count
r[property][:mean] = mean
unless no_std_dev
variance = values.inject(0.0) { |sum, value| diff = (value - mean) ; sum += diff * diff } / count
std = Math.sqrt(variance)
r[property][:std_dev] = std
end
end
end
end
def finalize
yield({:group => key, :count => size}.merge(:results => results))
end
register
end
end
end
Version data entries
5 entries across 5 versions & 2 rubygems