Sha256: eca835c73d2e1c1f73d35268669212fdf317f5bc5d1979099af1c5d46968d99b
Contents?: true
Size: 849 Bytes
Versions: 52
Compression:
Stored size: 849 Bytes
Contents
module Bmg
class Summarizer
#
# Variance summarizer
#
# Example:
#
# # direct ruby usage
# Bmg::Summarizer.variance(:qty).summarize(...)
#
class Variance < Summarizer
# Returns the least value.
def least()
[0, 0.0, 0.0]
end
# Aggregates on a tuple occurence.
def _happens(memo, val)
count, mean, m2 = memo
count += 1
delta = val - mean
mean += (delta / count)
m2 += delta*(val - mean)
[count, mean, m2]
end
# Finalizes the computation.
def finalize(memo)
count, mean, m2 = memo
m2 / count
end
end # class Variance
# Factors a variance summarizer
def self.variance(*args, &bl)
Variance.new(*args, &bl)
end
end # class Summarizer
end # module Bmg
Version data entries
52 entries across 52 versions & 1 rubygems