clojure - 关于序列转换的惯用 Clojure 问题

Question

我正在学习 Clojure，我需要在正确的方向上插入我提出的这个问题。

我有一系列事件。每个事件都包含一个“日期”。

(def events
  [
   [1509 :marry   "Catherine of Aragon"]
   [1527 :unmarry "Catherine of Aragon"]
   [1533 :marry   "Anne Boleyn"]
   [1536 :unmarry "Anne Boleyn"]
   [1536 :marry   "Jane Seymour"]
   [1537 :unmarry "Jane Seymour"]
   [1540 :marry   "Anne of Cleves"]
   [1540 :unmarry "Anne of Cleves"]
   [1540 :marry   "Catherine Howard"]
   [1542 :unmarry "Catherine Howard"]
   [1543 :marry   "Catherine Parr"]])

我想将其转换为惰性时间线，即每年包含一个向量的序列。从第一个事件发生的年份开始，一直到无穷大。

[[[:marry "Catherine of Aragon"]] [] [] [] [] [] [] [] [] [] [] [] [] [] [] [] [] [] [[:unmarry "Catherine of Aragon"]] [] [] [] [] [] [[:marry "Ane Boleyn"]] [] [] [[:unmarry "Anne Boleyn"] [:marry "Jayne Seymour"]] ...]

Answer 1

(def timeline
  (let [events-by-year (group-by first events)]
    (map #(map next (events-by-year %))
      (iterate inc (reduce min (keys events-by-year))))))

快速测试:

=> (take 30 timeline)
(((:marry "Catherine of Aragon")) () () () () () () () () () () () () () () () ()
 () ((:unmarry "Catherine of Aragon")) () () () () () ((:marry "Anne Boleyn")) ()
 () ((:unmarry "Anne Boleyn") (:marry "Jane Seymour")) ((:unmarry "Jane Seymour"))
 ())