Question

我在clojure中有一个地图数据结构：

{：category_id 1，：name“ELECTRONICS”，：lft 1，：rgt 20，：children [{：category_id 6，：name“PORTABLE ELECTRONICS”，：lft 10，：rgt 19，：children [{：children [{：rgt 13，：lft 12，：name“FLASH”，：category_id 8}]，：category_id 7，：name“MP3 PLAYERS”，：lft 11，：rgt 14} {：rgt 18，：lft 17，：名称“2 WAY RADIOS”，：category_id 10} {：rgt 16，：lft 15，：name“CD PLAYERS”，：category_id 9}]} {：children [{：rgt 6，：lft 5 ，：name“LCD”，：category_id 4} {：rgt 8，：lft 7，：name“PLASMA”，：category_id 5} {：rgt 4，：lft 3 ,: name“TUBE”，：category_id 3}] ，：rgt 9，：lft 2 ,: name“TELEVISIONS”，：category_id 2}]}

我想将一些数据（与类别相关联的产品）附加到作为产品类别的所有叶节点，以便它看起来像这样：

{：category_id 1，：name“ELECTRONICS”，：lft 1，：rgt 20，：children [{：category_id 6，：name“PORTABLE ELECTRONICS”，：lft 10，：rgt 19，：children [{：children [{：rgt 13，：lft 12，：name“FLASH”，：category_id 8}]，：category_id 7，：name“MP3 PLAYERS”，：lft 11，：rgt 14：products [{：name “SONY MP3 PLAYER”} {：name“SONY MP3 PLAYER 2”}}} {：rgt 18，：lft 17，：name“2 WAY RADIOS”，：category_id 10} {：rgt 16，：lft 15，：name “CD播放器”，：category_id 9}]} {：children [{：rgt 6，：lft 5，：name“LCD”，：category_id 4} {：rgt 8，：lft 7，：name“PLASMA”，： category_id 5} {：rgt 4，：lft 3，：name“TUBE”，：category_id 3}]，：rgt 9，：lft 2，：name“TELEVISIONS”，：category_id 2}]}

我已将两个产品添加到叶节点“MP3播放器”

如何使用clojure实现这一目标？如果不是clojure，我可以用任何其他编程语言获得解决方案吗？像Python等。？

Answer 1

假设您不知道您的类别位于层次结构中的哪个位置，您可以使用此方法：

(use 'clojure.walk)

(defn add-to-category
  [catalog cat-id product]
  (postwalk (fn [x]
              (if (and (map? x)
                       (= (:category_id x) cat-id))
                (update-in x [:products] conj product)
                x))
            catalog))

这是您的初始地图：

(def my-catalog {:children
 [{:children
   [{:children [{:name "FLASH", :lft 12, :category_id 8, :rgt 13}],
     :name "MP3 PLAYERS",
     :lft 11,
     :category_id 7,
     :rgt 14}
    {:name "2 WAY RADIOS", :lft 17, :category_id 10, :rgt 18}
    {:name "CD PLAYERS", :lft 15, :category_id 9, :rgt 16}],
   :name "PORTABLE ELECTRONICS",
   :lft 10,
   :category_id 6,
   :rgt 19}
  {:children
   [{:name "LCD", :lft 5, :category_id 4, :rgt 6}
    {:name "PLASMA", :lft 7, :category_id 5, :rgt 8}
    {:name "TUBE", :lft 3, :category_id 3, :rgt 4}],
   :name "TELEVISIONS",
   :lft 2,
   :category_id 2,
   :rgt 9}],
 :name "ELECTRONICS",
 :lft 1,
 :category_id 1,
 :rgt 20}

调用为：

(add-to-category my-catalog 7 {:name "SONY MP3 PLAYER 2"})

Answer 2

这看起来像是update-in的工作。

(def categories {:category_id 1, :name "ELECTRONICS", :lft 1, :rgt 20, :children [{:category_id 6, :name "PORTABLE ELECTRONICS", :lft 10, :rgt 19, :children [{:children [{:rgt 13, :lft 12, :name "FLASH", :category_id 8}], :category_id 7, :name "MP3 PLAYERS", :lft 11, :rgt 14} {:rgt 18, :lft 17, :name "2 WAY RADIOS", :category_id 10} {:rgt 16, :lft 15, :name "CD PLAYERS", :category_id 9}]} {:children [{:rgt 6, :lft 5, :name "LCD", :category_id 4} {:rgt 8, :lft 7, :name "PLASMA", :category_id 5} {:rgt 4, :lft 3, :name "TUBE", :category_id 3}], :rgt 9, :lft 2, :name "TELEVISIONS", :category_id 2}]})

(update-in categories [:children 0 :children 0 :products]
                      conj {:name "SONY MP3 PLAYER"} {:name "SONY MP3 PLAYER 2"})

;; Returns a similar giant map. Here with clojure.pprint/pprint formatting:
{:category_id 1,
 :name "ELECTRONICS",
 :lft 1,
 :rgt 20,
 :children
 [{:category_id 6,
   :name "PORTABLE ELECTRONICS",
   :lft 10,
   :rgt 19,
   :children
   [{:products ({:name "SONY MP3 PLAYER 2"} {:name "SONY MP3 PLAYER"}),
     :children [{:rgt 13, :lft 12, :name "FLASH", :category_id 8}],
     :category_id 7,
     :name "MP3 PLAYERS",
     :lft 11,
     :rgt 14}
    {:rgt 18, :lft 17, :name "2 WAY RADIOS", :category_id 10}
    {:rgt 16, :lft 15, :name "CD PLAYERS", :category_id 9}]}
  {:children
   [{:rgt 6, :lft 5, :name "LCD", :category_id 4}
    {:rgt 8, :lft 7, :name "PLASMA", :category_id 5}
    {:rgt 4, :lft 3, :name "TUBE", :category_id 3}],
   :rgt 9,
   :lft 2,
   :name "TELEVISIONS",
   :category_id 2}]}

如果您特别需要:products作为向量，那么您希望代替conj使用创建向量的函数（如果它已通过nil }作为第一个参数。 conj should work this way starting in 1.7，但我必须提供的测试时间早于此。

如何将数据附加到clojure地图的所有叶节点？

2 个答案: