Clojure嵌套地图-更改值

Posted 2021-04-15

不得不说，我大约在两周前开始学习Clojure，但自整整三天以来，我一直在遇到问题。

我有这样的地图：

{
  :agent1 {:name "Doe" :firstname "John" :state "a" :time "VZ" :team "X"}
  :agent2 {:name "Don" :firstname "Silver" :state "a" :time "VZ" :team "X"}
  :agent3 {:name "Kim" :firstname "Test" :state "B" :time "ZZ" :team "G"}
}

并且需要将:team "X"更改为:team "H"。我尝试了很多东西，例如assoc，update-in等，但无济于事。

我该怎么办？非常感谢！

答案

关联用于在路径指定的映射中替换或插入值

(def m { :agent1 {:name "Doe" :firstname "John" :state "a" :time "VZ" :team "X"}
         :agent2 {:name "Don" :firstname "Silver" :state "a" :time "VZ" :team "X"}
         :agent3 {:name "Kim" :firstname "Test" :state "B" :time "ZZ" :team "G"}})

(assoc-in m [:agent1 :team] "H")

{:agent1 {:state "a", :team "H", :name "Doe", :firstname "John", :time "VZ"},
 :agent2 {:state "a", :team "X", :name "Don", :firstname "Silver", :time "VZ"},
 :agent3 {:state "B", :team "G", :name "Kim", :firstname "Test", :time "ZZ"}}

但是，如果要在树的所有递归级别上更新所有团队“ X”，无论特定路径如何，都可以将clojure.walk的prewalk或postwalk函数与您自己的函数结合使用：

(use 'clojure.walk)
(defn postwalk-mapentry
    [smap nmap form]
    (postwalk (fn [x] (if (= smap x) nmap x)) form))

(postwalk-mapentry [:team "X"] [:team "T"] m)

{:agent1 {:state "a", :team "T", :name "Doe", :firstname "John", :time "VZ"},
 :agent2 {:state "a", :team "T", :name "Don", :firstname "Silver", :time "VZ"},
 :agent3 {:state "B", :team "G", :name "Kim", :firstname "Test", :time "ZZ"}}

另一答案

步行功能非常适合替换。

(clojure.walk/prewalk-replace {[:team "X"] [:team "H"]} map)

传递向量可以确保您不只是替换所有的“ X”。