list - 从列表中删除重复项并在 Lisp 中组合它

Question

我有以下类型的列表

(("abc" "12" "45")
 ("abc" "34" "56")
 ("cdb" "56" "78")
 ("deg" "90" "67")
 ("deg" "45" "34"))

所需的输出是

(("abc" "12" "45" "34" "56")
 ("cdb" "56" "78")
 ("deg" "90" "67" "45 "34)).

Lisp 中相同的正确方法是什么？

Answer 1

在 Common Lisp 中，一种可能是这样的:

(defun merge-lists (lists)
  (let ((rv (make-hash-table :test #'equal)))
         (mapcar (lambda (list)
           (mapcar (lambda (x) (push x (gethash (car list) rv nil))) (cdr list)))
                   lists)
    (loop for key being the hash-keys of rv
          collect (cons key (reverse (gethash key rv))))))