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x/avg and rfs/avg return nil when no input

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Christophe Grand 2018-06-13 18:08:34 +02:00
parent c65e766395
commit bae87d1b50
1 changed files with 6 additions and 4 deletions
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10
src/net/cgrand/xforms/rfs.cljc
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@ -55,11 +55,13 @@
(defn avg
"Reducing fn to compute the arithmetic mean."
([] (transient [0 0]))
([[n sum]] (/ sum n))
([] nil)
([^doubles acc] (when acc (/ (aget acc 1) (aget acc 0))))
([acc x] (avg acc x 1))
([[n sum :as acc] x w] ; weighted mean
(-> acc (assoc! 0 (+ n w)) (assoc! 1 (+ sum (* w x))))))
([^doubles acc x w] ; weighted mean
(doto (or acc #?(:clj (double-array 3) :cljs #js [0.0 0.0]))
(aset 0 (+ (aget acc 0) w))
(aset 1 (+ (aget acc 1) (* w x))))))
(defn sd
"Reducing fn to compute the standard deviation. Returns 0 if no or only one item."