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Implements first case subsampling function.

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This commit is contained in:
Ryan Boldi 2022-03-14 19:04:32 -04:00
parent 22b7067f10
commit 43fde4c7ad
2 changed files with 43 additions and 9 deletions
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40
src/propeller/downsample.cljc
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@ -1,5 +1,7 @@
(ns propeller.downsample
(:require [propeller.tools.math :as math]))
(:require [propeller.tools.math :as math]
[propeller.tools.metrics :as metrics]
[propeller.utils :as utils]))
(defn assign-indices-to-data
"assigns an index to each training case in order to differentiate them when downsampling"
@ -18,6 +20,32 @@
[training-data {:keys [downsample-rate]}]
(take (int (* downsample-rate (count training-data))) (shuffle training-data)))
(defn select-downsample-tournament
"uses case-tournament selection to select a downsample that is biased to being spread out"
[training-data {:keys [downsample-rate case-t-size]}]
(let [shuffled-cases (shuffle training-data)
goal-size (int (* downsample-rate (count training-data)))]
(loop [new-downsample (conj [] (first shuffled-cases))
cases-to-pick-from (rest shuffled-cases)]
;(prn {:new-downsample new-downsample :cases-to-pick-from cases-to-pick-from})
(if (>= (count new-downsample) goal-size)
new-downsample
(let [tournament (take case-t-size cases-to-pick-from)
rest-of-cases (drop case-t-size cases-to-pick-from)
case-distances (metrics/mean-of-colls
(map (fn [distance-list]
(utils/filter-by-index distance-list (map #(:index %) tournament)))
(map #(:distances %) new-downsample)))
selected-case-index (metrics/argmax case-distances)]
(prn {:avg-case-distances case-distances :selected-case-index selected-case-index})
(recur (conj new-downsample (nth tournament selected-case-index))
(shuffle (concat (utils/drop-nth selected-case-index tournament)
rest-of-cases))))))))
(defn select-downsample-metalex
"uses meta-lexicase selection to select a downsample that is biased to being spread out"
[training-data {:keys [downsample-rate]}])
(defn get-distance-between-cases
"returns the distance between two cases given a list of individual error vectors, and the index these
cases exist in the error vector"
@ -54,7 +82,9 @@
individuals performance on the each case in the ds-data, in order"
[evaluated-pop ds-data training-data]
(let [ds-indices (map #(:index %) ds-data) errors (map #(:errors %) evaluated-pop)]
(merge-map-lists-at-index training-data
(map-indexed (fn [idx d-case]
(update-in d-case [:distances] #(update-at-indices %
(map (fn [other] (get-distance-between-cases errors idx other)) (range (count ds-indices))) ds-indices))) ds-data))))
(merge-map-lists-at-index
training-data (map-indexed
(fn [idx d-case] (update-in d-case
[:distances] #(update-at-indices
% (map (fn [other] (get-distance-between-cases errors idx other))
(range (count ds-indices))) ds-indices))) ds-data))))

8
src/propeller/gp.cljc
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@ -49,7 +49,9 @@
(range population-size))
indexed-training-data (downsample/assign-indices-to-data (downsample/initialize-case-distances argmap))]
(let [training-data (if (= (:parent-selection argmap) :ds-lexicase)
(downsample/select-downsample-random indexed-training-data argmap)
(case (:ds-function argmap)
:case-tournament (downsample/select-downsample-tournament indexed-training-data argmap)
(downsample/select-downsample-random indexed-training-data argmap)) ;defaults to random
indexed-training-data)
evaluated-pop (sort-by :total-error
(mapper
@ -93,4 +95,6 @@
(first evaluated-pop))
(repeatedly population-size
#(variation/new-individual evaluated-pop argmap)))
(if (= (:parent-selection argmap) :ds-lexicase) (downsample/update-case-distances evaluated-pop training-data indexed-training-data) indexed-training-data))))))
(if (= (:parent-selection argmap) :ds-lexicase)
(downsample/update-case-distances evaluated-pop training-data indexed-training-data)
indexed-training-data))))))