List 我可以吗;转置;在Clojure中将地图列表转换为列表地图?
嗨,huys:我想映射一个映射中所有值的“平均值”。假设我有一个地图列表:List 我可以吗;转置;在Clojure中将地图列表转换为列表地图?,list,map,clojure,transpose,List,Map,Clojure,Transpose,嗨,huys:我想映射一个映射中所有值的“平均值”。假设我有一个地图列表: [{"age" 2 "height" 1 "weight" 10}, {"age" 4 "height" 4 "weight" 20}, {"age" 7 "height" 11 "weight" 40}] 我想要的结果是 {"age 5 "height" 5 ....} ///下面是我脑子里的胡言乱语,也就是说,我可能会想象这在Clojure工作的方式……不要太认真 转换列表: {"age" [2 4 7] "
[{"age" 2 "height" 1 "weight" 10},
{"age" 4 "height" 4 "weight" 20},
{"age" 7 "height" 11 "weight" 40}]
我想要的结果是
{"age 5 "height" 5 ....}
///下面是我脑子里的胡言乱语,也就是说,我可能会想象这在Clojure工作的方式……不要太认真
转换列表:
{"age" [2 4 7] "height" [1 4 11] }
然后我可以做一些简单的事情,比如(再次,在这里构造一个名为freduce的函数)
得到
{“年龄”5“体重”10“身高”7}
看看
下面是我的一些实际代码:
(let [maps [{"age" 2 "height" 1 "weight" 10},
{"age" 4 "height" 4 "weight" 20},
{"age" 7 "height" 11 "weight" 40}]]
(->> (apply merge-with #(conj %1 %2)
(zipmap (apply clojure.set/union (map keys maps))
(repeat [])) ; set the accumulator
maps)
(map (fn [[k v]] [k (/ (reduce + v) (count v))]))
(into {})))
这里有一个相当详细的解决方案。希望有人能想出更好的办法:
(let [maps [{"age" 2 "height" 1 "weight" 10},
{"age" 4 "height" 4 "weight" 20},
{"age" 7 "height" 11 "weight" 40}]
ks (keys (first maps))
series-size (count maps)
avgs (for [k ks]
(/ (reduce +
(for [m maps]
(get m k)))
series-size))]
(zipmap ks avgs))
创建矢量图: (reduce (fn [m [k v]] (assoc m k (conj (get m k []) v))) {} (apply concat list-of-maps)) (减少(fn[m[k v]] (assocmk(conj(get mk[])v))) {} (应用concat地图列表) 创建平均值地图: (reduce (fn [m [k v]] (assoc m k (/ (reduce + v) (count v)))) {} map-of-vectors) (减少(fn[m[k v]] (关联m k(/(减少+v)(计数v))) {} 矢量图)
下面是另一个版本,它使用merge with with with without zipmap
(let [data [{:a 1 :b 2} {:a 2 :b 4} {:a 4 :b 8}]
num-vals (count data)]
(->> data (apply merge-with +)
(reduce (fn [m [k v]] (assoc m k (/ v num-vals))) {})))
演示
user=> (def data-list [{"age" 2 "height" 1 "weight" 10},
{"age" 4 "height" 4 "weight" 20},
{"age" 7 "height" 11 "weight" 40}])
#'user/data-list
user=> (key-join data-list)
{"age" (2 4 7), "height" (1 4 11), "weight" (10 20 40)}
user=> (mapf average (key-join data-list))
{"age" 13/3, "height" 16/3, "weight" 70/3}
以下是我的一行解决方案:
(def d [{"age" 2 "height" 1 "weight" 10},
{"age" 4 "height" 4 "weight" 20},
{"age" 7 "height" 11 "weight" 40}])
(into {} (map (fn [[k v] [k (/ v (count d))]]) (apply merge-with + d)))
=> {"height" 16/3, "weight" 70/3, "age" 13/3}
逻辑如下:
- 在地图上使用“与+合并”来计算每个键值的总和
- 将所有结果值除以贴图总数以获得平均值
- 将结果放回具有(到{}…)的hashmap中
+
合并为#(+(或%1 0)(或%2 0))
我认为,你的解决方案是正确的,因为它可读性很强。这很优雅,但在这一点上对我来说可能有点太高级了。感谢你指点我合并,我会学到它…似乎有道理。不确定平均值应用在哪里…我想是mapf>?如果你说如果函数名。>不确定平均值应用于何处。平均值应用于地图数据值(集合)。“平均值”不会应用于地图键。更不用说,减少(!)平均地图数据。感谢您的解释…有意义。
user=> (def data-list [{"age" 2 "height" 1 "weight" 10},
{"age" 4 "height" 4 "weight" 20},
{"age" 7 "height" 11 "weight" 40}])
#'user/data-list
user=> (key-join data-list)
{"age" (2 4 7), "height" (1 4 11), "weight" (10 20 40)}
user=> (mapf average (key-join data-list))
{"age" 13/3, "height" 16/3, "weight" 70/3}
(def d [{"age" 2 "height" 1 "weight" 10},
{"age" 4 "height" 4 "weight" 20},
{"age" 7 "height" 11 "weight" 40}])
(into {} (map (fn [[k v] [k (/ v (count d))]]) (apply merge-with + d)))
=> {"height" 16/3, "weight" 70/3, "age" 13/3}