在列表中找到原子的位置 [英] find the position of an atom in list
问题描述
我有一个带有原子T的板,我想获得列表和子列表中的位置
I have this board with atom T and I wanna get is position in list and sub-list
(defun board ()
"position of T: i=0 e j=9"
'(
;; 0 1 2 3 4 5 6 7 8 9
(96 25 54 89 21 8 36 14 41 T) ;; 0
(78 47 56 23 5 NIL 13 12 26 60) ;; 1
(0 27 17 83 34 93 74 52 45 80) ;; 2
(69 9 77 95 55 39 91 73 57 30) ;; 3
(24 15 22 86 1 11 68 79 76 72) ;; 4
(81 48 32 2 64 16 50 37 29 71) ;; 5
(99 51 6 18 53 28 7 63 10 88) ;; 6
(59 42 46 85 90 75 87 43 20 31) ;; 7
(3 61 58 44 65 82 19 4 35 62) ;; 8
(33 70 84 40 66 38 92 67 98 97);; 9
)
)
从电路板上获取行和单元格的功能
Function to get line and cell from board
(defun line (x board)
(nth x board))
(defun cell-board (x y board)
(nth y (line x board)))
(defun column (index board)
(cond ((not (numberp index)) nil)
((< index 0) nil)
(t (mapcar #'(lambda (line &aux (n-column (nth index line))) n-column) board))))
接收板并返回"T"所在位置(i j)的功能.如果板上没有"T",则应返回NIL.
Function that receives the board and returns the position (i j) where the "T" is. If "T" is not on the board, NIL should be returned.
(defun find-T-position (board)
)
您可以在此处进行测试并查看结果 https://ideone.com/GQIePI
you can teste and see the result here https://ideone.com/GQIePI
(打印"position:"(找到T位置(木板)))
(print "position : " (find-T-position (board)))
正确的结果应该是
(0 9)
(0 9)
推荐答案
I find the answer in this question Lisp position of nested list element with children and it´s work perfectly
(defun my-position (elm tree &optional (start 0))
"find the generalized position of elm inside tree.
Parameters: elm - element to be found
tree - a list of atoms and lists in which to search the element
start - the tentative position"
(cond ((null tree) nil) ; element not present => nil
((atom (first tree)) ; if the first element is an atom, then
(if (eql elm (first tree)) ; if equal to element, found
(list start) ; return position start
;; otherwise, recur on rest of list incrementing the tentative position
(my-position elm (rest tree) (1+ start))))
;; otherwise, the first element is a list,
;; try to find it inside, with a recursive call
(t (let ((pos (my-position elm (first tree) 0)))
(if pos ; if not nil the element has been found
(cons start pos) ; return the current position followed by the position inside the list
; otherwise recur on rest of list incrementing the tentative position
(my-position elm (rest tree) (1+ start)))))))
和我的函数find-t-position只调用函数my-position 包含元素'T和木板,并返回元素'T在 列表
and my function find-t-position just call the function my-position with element 'T and the board and return the position of element 'T in list
(defun find-T-position (board)
(my-position ('T board))
您可以看到正确的结果 https://ideone.com/DOIOoB
you can see the correct result https://ideone.com/DOIOoB
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