Merge branch 'friendlier-koans'
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commit
f30feb25fe
@ -1,5 +1,6 @@
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(ns koans.04-sets
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(:require [koan-engine.core :refer :all]))
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(:require [koan-engine.core :refer :all]
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[clojure.set :as set]))
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(meditations
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"You can create a set by converting another collection"
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@ -12,10 +13,10 @@
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(= __ (set '(1 1 2 2 3 3 4 4 5 5)))
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"You can ask clojure for the union of two sets"
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(= __ (clojure.set/union #{1 2 3 4} #{2 3 5}))
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(= __ (set/union #{1 2 3 4} #{2 3 5}))
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"And also the intersection"
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(= __ (clojure.set/intersection #{1 2 3 4} #{2 3 5}))
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(= __ (set/intersection #{1 2 3 4} #{2 3 5}))
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"But don't forget about the difference"
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(= __ (clojure.set/difference #{1 2 3 4 5} #{2 3 5})))
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(= __ (set/difference #{1 2 3 4 5} #{2 3 5})))
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@ -19,20 +19,20 @@
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"You can also group by a primary key"
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(= __
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(group-by :id [{:id 1 :name "Bob"}
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{:id 2 :name "Mike"}
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{:id 2 :name "Jennifer"}
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{:id 1 :last-name "Smith"} ]))
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"But be careful when you group by non-required key"
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(= {"Bob" [{:name "Bob" :id 1}]
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"Mike" [{:name "Mike" :id 2}]
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"Jennifer" [{:name "Jennifer" :id 2}]
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__ [{:last-name "Smith" :id 1}]}
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(group-by :name [{:id 1 :name "Bob"}
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{:id 2 :name "Mike"}
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{:id 2 :name "Jennifer"}
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{:id 1 :last-name "Smith"}]))
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"The true power of group-by comes with custom functions"
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(= __
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(group-by #(if (:bad %) :naughty-list :nice-list)
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[{:name "Jimmy" :bad true}
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{:name "Jack" :bad false}
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{:name "Anna" :bad false}
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{:name "Joe" :bad true}])))
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