[英]Clojure - Recursively Flatten Nested Maps
Given a map with the key :content, where content is a list of strings or other maps, how can I flatten out the values to receive only the strings? 给定一个带有键的映射:content,其中content是字符串列表或其他映射,如何将值展平以仅接收字符串?
(flattener {:content '("b" {:content ("c" {:content ("d")})} "e")})
> '("b" "c" "d" "e")
I'm stumbling through very hacky loop recur attempts and now my brain is burnt out. 我正在磕磕绊绊地进行非常粗暴的循环重复尝试,现在我的大脑被烧毁了。 Is there a nice idiomatic way to do this in Clojure?
在Clojure中有一个很好的惯用方法吗?
Thanks. 谢谢。
What I've got is below, and although it works, it's quite ugly 我得到的是下面的,虽然它有效,但它很难看
(defn flatten-content
[coll]
(loop [acc '(), l coll]
(let [fst (first l), rst (rest l)]
(cond
(empty? l) (reverse acc)
(seq? fst) (recur acc (concat fst rst))
(associative? fst) (recur acc (concat (:content fst) rst))
:else (recur (conj acc fst) rst)))))
The tree-seq
function helps walk, and since your map tree-seq
函数可以帮助您行走,也可以自动映射
(def m {:content '("b" {:content ("c" {:content ("d")})} "e")})
always has a list of "children" keyed by :content
, this works 总是有一个“孩子”的列表键入
:content
,这是有效的
(filter string? (tree-seq associative? :content m))
;=> ("b" "c" "d" "e")
The following recursive function works (and is about 25% faster than a filter
ed tree-seq
approach): 以下递归函数有效(并且比
filter
ed tree-seq
方法快25%):
(defn flatten-content [node]
(lazy-seq
(if (string? node)
(list node)
(mapcat flatten-content (:content node)))))
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.