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recursion - 如何在clojure中对嵌套序列进行排序？

问题描述

我有一个嵌套映射，其中键是数字，如下所示：

{:18 [Lan Yuhong 165 Happy Lane 345-4533], :33 [Man Yuhong 165 Happy Lane 345-4533], :3 [Tan Yuhong 165 Happy Lane 345-4533], :6 [Jan Yuhong 165 Happy Lane 345-4533], :5 [Han Yuhong 165 Happy Lane 345-4533], :7 [Fan Yuhong 165 Happy Lane 345-4533], :1 [Sue Jones 43 Rose Court Street 345-7867], :9 [John Smith 123 Here Street 456-4567]}

我想根据第一个条目（即键）进行排序，如下所示：

{:1 [Sue Jones 43 Rose Court Street 345-7867], :3 [Tan Yuhong 165 Happy Lane 345-4533], :5 [Han Yuhong 165 Happy Lane 345-4533], :6 [Jan Yuhong 165 Happy Lane 345-4533], :7 [Fan Yuhong 165 Happy Lane 345-4533], :9 [John Smith 123 Here Street 456-4567], :18 [Lan Yuhong 165 Happy Lane 345-4533], :33 [Man Yuhong 165 Happy Lane 345-4533]}

但是，每个列表中的第一个条目被视为字符串而不是整数，并sort/sort-by 返回按字典顺序排序的列表，如下所示。请注意，mps 存储在new-map我程序的变量中。

(do
    (into (sorted-map) new-map)
)

输出是：

([1 Sue Jones 43 Rose Court Street 345-7867] [18 Lan Yuhong 165 Happy Lane 345-4533] [3 Tan Yuhong 165 Happy Lane 345-4533] [33 Man Yuhong 165 Happy Lane 345-4533] [5 Han Yuhong 165 Happy Lane 345-4533] [6 Jan Yuhong 165 Happy Lane 345-4533] [7 Fan Yuhong 165 Happy Lane 345-4533] [9 John Smith 123 Here Street 456-4567])

我怎样才能在不使用任何循环的情况下做到这一点？我试图避免在这里使用循环。但是，递归函数是可以的。

标签： recursionclojurefunctional-programmingnested-lists

解决方案

你几乎拥有它。只需添加：

(sort-by #(Integer/parseInt (first %)) new-list)

完整代码：

(ns tst.demo.core
  (:use tupelo.core tupelo.test))

(dotest
  (let [data [["18" "Lan Yuhong" "165" "Happy Lane" "345-4533"]
              ["33" "Man Yuhong" "165" "Happy Lane" "345-4533"]
              ["3" "Tan Yuhong" "165" "Happy Lane" "345-4533"]
              ["6" "Jan Yuhong" "165" "Happy Lane" "345-4533"]
              ["5" "Han Yuhong" "165" "Happy Lane" "345-4533"]
              ["7" "Fan Yuhong" "165" "Happy Lane" "345-4533"]
              ["1" "Sue Jones" "43" "Rose Court Street" "345-7867"]
              ["9" "John Smith" "123 Here Street" "456-4567"]]]
    (spyx-pretty (sort-by #(Integer/parseInt (first %)) data))))

结果

(["1" "Sue Jones" "43" "Rose Court Street" "345-7867"]
 ["3" "Tan Yuhong" "165" "Happy Lane" "345-4533"]
 ["5" "Han Yuhong" "165" "Happy Lane" "345-4533"]
 ["6" "Jan Yuhong" "165" "Happy Lane" "345-4533"]
 ["7" "Fan Yuhong" "165" "Happy Lane" "345-4533"]
 ["9" "John Smith" "123 Here Street" "456-4567"]
 ["18" "Lan Yuhong" "165" "Happy Lane" "345-4533"]
 ["33" "Man Yuhong" "165" "Happy Lane" "345-4533"])

更新

对于您修改后的问题，请参阅函数 group-by

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