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loss.clj
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loss.clj
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(ns tech.ml.loss
(:require [clojure.core.matrix :as m]))
(defn mse
"mean squared error"
^double [predictions labels]
(assert (= (count predictions) (count labels)))
(let [n (count predictions)]
(double
(/ (-> (m/sub predictions labels)
(m/pow 2)
(m/esum))
n))))
(defn classification-accuracy
"correct/total.
Model output is a sequence of probability distributions.
label-seq is a sequence of values. The answer is considered correct
if the key highest probability in the model output entry matches
that label."
^double [model-output label-seq]
(let [num-items (count model-output)
num-correct (->> model-output
(map #(apply max-key % (keys %)))
(map vector label-seq)
(filter #(apply = %))
count)]
(/ (double num-correct)
(double num-items))))
(defn classification-loss
"1.0 - classification-accuracy."
^double [model-output label-seq]
(- 1.0
(classification-accuracy model-output label-seq)))