Question

我有一个函数，它输出一个看起来像这样的地图列表：

({:size20160721 "19.94 GB", :size20160720 "19.94 GB", :size20160719 "100 GB", :directory_path "/user/1 "}
 {:size20160721 "1 GB", :size20160720 "4 GB", :size20160719 "10 GB", :directory_path "/user/2 "}
 ...
 )

如何重新排序这个地图列表，以便每个地图首先包含：directory_path，然后是：size keys，其数量可以变化，但对于所有路径都是相同的？

Answer 1

使用sorted-map-by，比较器始终设置:directory_path：

user> 
(def data '({:size20160721 "19.94 GB", :size20160720 "19.94 GB",
             :size20160719 "100 GB", :directory_path "/user/1 "}
            {:size20160721 "1 GB", :size20160720 "4 GB",
             :size20160719 "10 GB", :directory_path "/user/2 "}))
;; #'user/data

user> 
(def dirfirst (sorted-map-by #(cond (= :directory_path %1) -1
                                    (= :directory_path %2) 1
                                    :else (compare %1 %2))))
;; #'user/dirfirst

user> (map (partial into dirfirst) data)

;; ({:directory_path "/user/1 ", :size20160719 "100 GB", 
;;   :size20160720 "19.94 GB", :size20160721 "19.94 GB"}
;;  {:directory_path "/user/2 ", :size20160719 "10 GB", 
;;   :size20160720 "4 GB", :size20160721 "1 GB"})

在地图列表中的地图中重新加载键

1 个答案: