假设我们有一个数据框或矩阵,其中一列指定整数值 N,如下所示(第 5 列)。是否有一种矢量方法来重新填充对象,使得每一行都被复制 N 次?
> y
[,1] [,2] [,3] [,4] [,5]
[1,] -0.02738267 0.5170621 -0.01644855 0.48830663 1
[2,] -0.30076544 1.8136359 0.02319640 -1.59649330 2
[3,] 1.73447245 0.4043638 -0.29112385 -0.25102988 3
[4,] 0.01025271 -0.4908636 0.80857300 0.08137033 4
结果如下。
[1,] -0.02738267 0.5170621 -0.01644855 0.48830663 1
[2,] -0.30076544 1.8136359 0.02319640 -1.59649330 2
[2,] -0.30076544 1.8136359 0.02319640 -1.59649330 2
[3,] 1.73447245 0.4043638 -0.29112385 -0.25102988 3
[3,] 1.73447245 0.4043638 -0.29112385 -0.25102988 3
[3,] 1.73447245 0.4043638 -0.29112385 -0.25102988 3
[4,] 0.01025271 -0.4908636 0.80857300 0.08137033 4
[4,] 0.01025271 -0.4908636 0.80857300 0.08137033 4
[4,] 0.01025271 -0.4908636 0.80857300 0.08137033 4
[4,] 0.01025271 -0.4908636 0.80857300 0.08137033 4
另一个问题是如何抖动新填充的行,使得新复制的数据不存在计算重叠。