请问如果不用nth,如何获取第二个点列表(10 25440.5 52216.8)。

3stone

((-1 . <图元名: 7ef99df0>) (0 . "LWPOLYLINE") (330 . <图元名: 7ef99c10>) (5 . "3E")
(100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "DM-坡度") (6 . "Continuous")
(100 . "AcDbPolyline") (90 . 3) (70 . 0) (38 . 0.0) (39 . 0.0) (10 25440.8
52215.1) (40 . 0.0) (41 . 0.0) (42 . 0.0) (10 25440.5 52216.8) (40 . 1.75) (41
. 0.0) (42 . 0.0) (10 25440.1 52218.5) (40 . 0.0) (41 . 0.0) (42 . 0.0) (210
0.0 0.0 1.0))
请问如果不用nth,如何获取第二个点列表(10 25440.5 52216.8)。

highflybir

(assoc 10 (cdr (member (assoc 10 elist) elist)))

3stone

如果一根多义线有多个点对，提取其中的第4个点，那有没有简洁的办法？

((-1 . <图元名: 7efb7fa0>) (0 . "LWPOLYLINE") (330 . <图元名: 7efb7c10>) (5 .
"74") (100 . "AcDbEntity") (67 . 0) (410 . "Model") (8 . "DX-三维模型") (6 .
"Continuous") (100 . "AcDbPolyline") (90 . 6) (70 . 128) (43 . 0.0) (38 . 0.0)
(39 . 0.0) (10 25464.4 52227.1) (40 . 0.0) (41 . 0.0) (42 . 0.0) (10 25469.7
52221.5) (40 . 0.0) (41 . 0.0) (42 . 0.0) (10 25464.7 52217.0) (40 . 0.0) (41 .
0.0) (42 . 0.0) (10 25469.9 52212.1) (40 . 0.0) (41 . 0.0) (42 . 0.0) (10
25465.2 52206.5) (40 . 0.0) (41 . 0.0) (42 . 0.0) (10 25470.0 52202.7) (40 .
0.0) (41 . 0.0) (42 . 0.0) (210 0.0 0.0 1.0))

Andyhon

;;; by Michael Puckett
    (defun cdrs (key lst / pair rtn)
      (while (setq pair (assoc key lst))
        (setq lst (cdr (member pair lst))
              rtn (cons (cdr pair) rtn)
      ) )
      (reverse rtn)
    );

usage:
(cdrs 10 DatLst)

无痕

(vlax-curve-getpointatparam obj 3)