class Bmg::Summarizer::Variance
Variance
summarizer
Example:
# direct ruby usage Bmg::Summarizer.variance(:qty).summarize(...)
Public Instance Methods
_happens(memo, val)
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Aggregates on a tuple occurence.
# File lib/bmg/summarizer/variance.rb, line 19 def _happens(memo, val) count, mean, m2 = memo count += 1 delta = val - mean mean += (delta / count) m2 += delta*(val - mean) [count, mean, m2] end
finalize(memo)
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Finalizes the computation.
# File lib/bmg/summarizer/variance.rb, line 29 def finalize(memo) count, mean, m2 = memo m2 / count end
least()
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Returns the least value.
# File lib/bmg/summarizer/variance.rb, line 14 def least() [0, 0.0, 0.0] end