[code]> mat[,1:6] [,1] [,2] [,3] [,4] [,5] [,6] [1,] 1778 1.89192605 1778 3.0242247 1778 4.2449375 [2,] 1779 2.52550859 1779 2.9363827 1779 2.3178877 [3,] 1780 1.40584686 1780 1.1512215 1780 1.6730327 [4,] 1781 2.76818929 1781 2.6100480 1781 2.4704876 [5,] 1782 2.79713009 1782 3.6626975 1782 2.8516042 [6,] 1783 -0.99733092 1783 -0.1093256 1783 -0.9590519 [7,] 1784 -1.12917237 1784 -0.5926512 1784 -1.2626489 [8,] 1785 1.03728150 1785 1.1202371 1785 0.5453972 [9,] 1786 0.94385189 1786 0.5727703 1786 0.9469920 [10,] 1787 0.06562888 1787 -0.2293504 1787 0.1102673 [11,] 1788 -0.63780107 1788 -0.4626972 1788 -0.7644880[/code]      如上所示，奇数行的坐标都是一样的，偶数行的数据不同