From bcf9b230be6d74c71567fd0771b31d47d8dd39c7 Mon Sep 17 00:00:00 2001
From: Brian Picciano <mediocregopher@gmail.com>
Date: Thu, 21 Jan 2021 17:22:53 -0700
Subject: build the blog with nix

---
 src/assets/viz/2/clojure/set.cljs | 161 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 161 insertions(+)
 create mode 100644 src/assets/viz/2/clojure/set.cljs

(limited to 'src/assets/viz/2/clojure/set.cljs')

diff --git a/src/assets/viz/2/clojure/set.cljs b/src/assets/viz/2/clojure/set.cljs
new file mode 100644
index 0000000..b9ba41f
--- /dev/null
+++ b/src/assets/viz/2/clojure/set.cljs
@@ -0,0 +1,161 @@
+;   Copyright (c) Rich Hickey. All rights reserved.
+;   The use and distribution terms for this software are covered by the
+;   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+;   which can be found in the file epl-v10.html at the root of this distribution.
+;   By using this software in any fashion, you are agreeing to be bound by
+;   the terms of this license.
+;   You must not remove this notice, or any other, from this software.
+
+(ns ^{:doc "Set operations such as union/intersection."
+       :author "Rich Hickey"}
+       clojure.set)
+
+(defn- bubble-max-key [k coll]
+  "Move a maximal element of coll according to fn k (which returns a number) 
+   to the front of coll."
+  (let [max (apply max-key k coll)]
+    (cons max (remove #(identical? max %) coll))))
+
+(defn union
+  "Return a set that is the union of the input sets"
+  ([] #{})
+  ([s1] s1)
+  ([s1 s2]
+     (if (< (count s1) (count s2))
+       (reduce conj s2 s1)
+       (reduce conj s1 s2)))
+  ([s1 s2 & sets]
+     (let [bubbled-sets (bubble-max-key count (conj sets s2 s1))]
+       (reduce into (first bubbled-sets) (rest bubbled-sets)))))
+
+(defn intersection
+  "Return a set that is the intersection of the input sets"
+  ([s1] s1)
+  ([s1 s2]
+     (if (< (count s2) (count s1))
+       (recur s2 s1)
+       (reduce (fn [result item]
+                   (if (contains? s2 item)
+		     result
+                     (disj result item)))
+	       s1 s1)))
+  ([s1 s2 & sets] 
+     (let [bubbled-sets (bubble-max-key #(- (count %)) (conj sets s2 s1))]
+       (reduce intersection (first bubbled-sets) (rest bubbled-sets)))))
+
+(defn difference
+  "Return a set that is the first set without elements of the remaining sets"
+  ([s1] s1)
+  ([s1 s2] 
+     (if (< (count s1) (count s2))
+       (reduce (fn [result item] 
+                   (if (contains? s2 item) 
+                     (disj result item) 
+                     result))
+               s1 s1)
+       (reduce disj s1 s2)))
+  ([s1 s2 & sets] 
+     (reduce difference s1 (conj sets s2))))
+
+
+(defn select
+  "Returns a set of the elements for which pred is true"
+  [pred xset]
+    (reduce (fn [s k] (if (pred k) s (disj s k)))
+            xset xset))
+
+(defn project
+  "Returns a rel of the elements of xrel with only the keys in ks"
+  [xrel ks]
+    (set (map #(select-keys % ks) xrel)))
+
+(defn rename-keys
+  "Returns the map with the keys in kmap renamed to the vals in kmap"
+  [map kmap]
+    (reduce
+     (fn [m [old new]]
+       (if (contains? map old)
+         (assoc m new (get map old))
+         m))
+     (apply dissoc map (keys kmap)) kmap))
+
+(defn rename
+  "Returns a rel of the maps in xrel with the keys in kmap renamed to the vals in kmap"
+  [xrel kmap]
+    (set (map #(rename-keys % kmap) xrel)))
+
+(defn index
+  "Returns a map of the distinct values of ks in the xrel mapped to a
+  set of the maps in xrel with the corresponding values of ks."
+  [xrel ks]
+    (reduce
+     (fn [m x]
+       (let [ik (select-keys x ks)]
+         (assoc m ik (conj (get m ik #{}) x))))
+     {} xrel))
+   
+(defn map-invert
+  "Returns the map with the vals mapped to the keys."
+  [m] (reduce (fn [m [k v]] (assoc m v k)) {} m))
+
+(defn join
+  "When passed 2 rels, returns the rel corresponding to the natural
+  join. When passed an additional keymap, joins on the corresponding
+  keys."
+  ([xrel yrel] ;natural join
+   (if (and (seq xrel) (seq yrel))
+     (let [ks (intersection (set (keys (first xrel))) (set (keys (first yrel))))
+           [r s] (if (<= (count xrel) (count yrel))
+                   [xrel yrel]
+                   [yrel xrel])
+           idx (index r ks)]
+       (reduce (fn [ret x]
+                 (let [found (idx (select-keys x ks))]
+                   (if found
+                     (reduce #(conj %1 (merge %2 x)) ret found)
+                     ret)))
+               #{} s))
+     #{}))
+  ([xrel yrel km] ;arbitrary key mapping
+   (let [[r s k] (if (<= (count xrel) (count yrel))
+                   [xrel yrel (map-invert km)]
+                   [yrel xrel km])
+         idx (index r (vals k))]
+     (reduce (fn [ret x]
+               (let [found (idx (rename-keys (select-keys x (keys k)) k))]
+                 (if found
+                   (reduce #(conj %1 (merge %2 x)) ret found)
+                   ret)))
+             #{} s))))
+
+(defn subset? 
+  "Is set1 a subset of set2?"
+  [set1 set2]
+  (and (<= (count set1) (count set2))
+       (every? #(contains? set2 %) set1)))
+
+(defn superset? 
+  "Is set1 a superset of set2?"
+  [set1 set2]
+  (and (>= (count set1) (count set2))
+       (every? #(contains? set1 %) set2)))
+
+(comment
+(refer 'set)
+(def xs #{{:a 11 :b 1 :c 1 :d 4}
+         {:a 2 :b 12 :c 2 :d 6}
+         {:a 3 :b 3 :c 3 :d 8 :f 42}})
+
+(def ys #{{:a 11 :b 11 :c 11 :e 5}
+         {:a 12 :b 11 :c 12 :e 3}
+         {:a 3 :b 3 :c 3 :e 7 }})
+
+(join xs ys)
+(join xs (rename ys {:b :yb :c :yc}) {:a :a})
+
+(union #{:a :b :c} #{:c :d :e })
+(difference #{:a :b :c} #{:c :d :e})
+(intersection #{:a :b :c} #{:c :d :e})
+
+(index ys [:b]))
+
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