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如何将向量映射到一个映射,将重复的键值推入其中?

hashmap clojure vector

Pedro Silva · 技术社区 · 14 年前

这是我的输入数据:

[[:a 1 2] [:a 3 4] [:a 5 6] [:b \a \b] [:b \c \d] [:b \e \f]]

我想将此映射为以下内容:

{:a [[1 2] [3 4] [5 6]] :b [[\a \b] [\c \d] [\e \f]]}

(defn- build-annotation-map [annotation & m]
 (let [gff (first annotation)
       remaining (rest annotation)
       seqname (first gff)
       current {seqname [(nth gff 3) (nth gff 4)]}]
   (if (not (seq remaining))
     m
     (let [new-m (merge-maps current m)]
       (apply build-annotation-map remaining new-m)))))

(defn- merge-maps [m & ms]
  (apply merge-with conj
         (when (first ms)                                                                                                              
           (reduce conj                     ;this is to avoid [1 2 [3 4 ... etc.                                                                                                          
                   (map (fn [k] {k []}) (keys m))))                                                                                    
         m ms))

以上产生:

{:a [[1 2] [[3 4] [5 6]]] :b [[\a \b] [[\c \d] [\e \f]]]}

merge-maps ,特别是传递给 merge-with ( conj ),但在撞了我的头一段时间后,我准备找人来帮我。

解决方案 (无论如何,离得够近了):

(group-by first [[:a 1 2] [:a 3 4] [:a 5 6] [:b \a \b] [:b \c \d] [:b \e \f]])
=> {:a [[:a 1 2] [:a 3 4] [:a 5 6]], :b [[:b \a \b] [:b \c \d] [:b \e \f]]}

5 回复 | 直到 14 年前

MayDaniel 14 年前

(defn build-annotations [coll]
  (reduce (fn [m [k & vs]]
            (assoc m k (conj (m k []) (vec vs))))
          {} coll))

annotation , gff seqname . current remaining 通常称为 more

在你的陈述中, gff (first annotation) remaining (rest annotation) ,我可能会利用解构,像这样:

(let [[first & more] annotation] ...)

(rest annotation) 那我建议用 next 相反,因为它会回来 nil 如果它是空的,允许你写 (if-not remaining ...) 而不是 (if-not (seq remaining) ...)

user> (next [])
nil
user> (rest [])
()

在Clojure中,与其他lisp不同,空列表是真实的。

This

ponzao 14 年前

(defn build-annotations [coll]
  (reduce
    (fn [result vec]
      (let [key (first vec)
            val (subvec vec 1)
            old-val (get result key [])
            conjoined-val (conj old-val val)]
        (assoc
          result
          key
          conjoined-val)))
    {}
    coll))

(build-annotations [[:a 1 2] [:a 3 4] [:a 5 6] [:b \a \b] [:b \c \d] [:b \e \f]])

很抱歉没有对你的代码进行改进。我只是在学习Clojure,一段一段地解决问题比理解更大的代码并从中发现问题更容易。

Thomas Wagner 14 年前

虽然我还没有对您的代码发表任何评论,但我自己也尝试过,并提出了以下解决方案:

(defn build-annotations [coll]
  (let [anmap (group-by first coll)]
    (zipmap (keys anmap) (map #(vec (map (comp vec rest) %)) (vals anmap)))))

Alex Miller 14 年前

下面是我的条目,虽然这里的几个步骤实际上是关于返回向量而不是列表。如果你放弃了这个要求,它会变得简单一些:

(defn f [s]
  (let [g (group-by first s)
        k (keys g)
        v (vals g)
        cleaned-v (for [group v]
                    (into [] (map (comp #(into [] %) rest) group)))]
    (zipmap k cleaned-v)))

取决于你真正想要什么,你甚至可以只做小组讨论。

wilkes 14 年前

(defn build-annotations [coll]
  (apply merge-with concat 
         (map (fn [[k & vals]] {k [vals]}) 
              coll))

(map (fn [[k & vals]] {k [vals]}) 
     coll))

获取[keys&values]的集合并返回{key[values]}的列表

(apply merge-with concat ...list of maps...)