在一群坐标点，一些坐标y值相同，例如y1，此时如何取得y1坐标下的x坐标最大的那个点？

onlooker

在n个坐标点时，一些坐标它们的y值是相同的，例如是y1,另外一些坐标它们的y值是y2,这个时候我需要取出来的是在y1坐标下，x坐标最大的哪个点，y2坐标下，x坐标最大的那个点，比如下列坐标点   lst '(100.0 100.0) '(115.0 100.0)        '(115.0 115.0) '(115.022 115.0)
                  '(100.0 120.834) '(130.0 130.0) '(140.0 130.0) '(160.0 155.0)
                  '(190.0 180.0) '(180.0 180.0)        '(190.0 190.0) '(200.0 190.0)
                  '(179.559 200.0) '(200.0 200.0))
要获得的坐标就是：（115.0 100.0 ） （100.0 120.834）（(140.0 130.0）（160.0 155.0）（190.0 180.0）（(200.0 190.0）（200.0 200.0）
论坛的大神们，求帮助啊！

onlooker

在线等待中，求解

fan_zh

(vl-sort lst
                     '(lambda (a b)
                        (if (equal (cadar a) (cadar b) 0.001)
                          (< (caar a) (caar b))
                          (> (cadar a) (cadar b))
                        )
                      )
            )
仅供参考

迷失1786

1,5369831.622,4827565.957,
2,5519053.344,4929086.315,
3,5703878.834,4912863.995,
4,5832680.754,4878326.141,
5,5952058.114,4813960.137,
6,5990279.833,4694647.554,
7,5962006.242,4624001.943,
8,5903364.721,4570625.259,
9,5755713.748,4574288.365,
10,5625341.079,4600453.410,
11,5480308.057,4607779.612,
12,5407006.139,4692554.352,
13,5359883.494,4776805.783,
14,5336845.762,4810297.030,
15,5336845.762,4840125.181,
16,5353076.886,4853207.703,
17,5367213.692,4853207.703,
18,5500204.269,4750640.739,
19,5585298.007,4762251.266,
20,5600551.150,4846768.070,
21,5524884.374,4887391.800,
22,5462866.591,4827981.842,
23,5635903.951,4822877.639,
24,5685603.635,4822877.639,
25,5685603.635,4793237.548,
26,5635903.951,4793237.548,
27,5710555.724,4819402.592,
28,5760255.408,4819402.592,
29,5760255.408,4789762.501,
30,5710555.724,4789762.501,
31,5787457.284,4804275.931,
32,5837156.968,4804275.931,
33,5837156.968,4774635.840,
34,5787457.284,4774635.840,
35,5837991.304,4746543.469,
36,5887690.988,4746543.469,
37,5887690.988,4716903.377,
38,5837991.304,4716903.377,
39,5851899.017,4693191.321,
40,5901598.701,4693191.321,
41,5901598.701,4663551.230,
42,5851899.017,4663551.230,
43,5793813.820,4658645.285,
44,5843513.503,4658645.285,
45,5843513.503,4629005.194,
46,5793813.820,4629005.194,
47,5702582.318,4667048.061,
48,5731829.465,4667048.061,
49,5731829.465,4641905.097,
50,5702582.318,4641905.097,