好的,我需要一个非常具体的子集筛选公式。从矩阵x中,我只想保留由行和列定义的元素。不需要的元素应该被零替换。以下是示例:
> x <- matrix(c(65,46,52,76,34,345,65,87,12,53),nrow = 5,ncol = 2)
> x
[,1] [,2]
[1,] 65 345
[2,] 46 65
[3,] 52 87
[4,] 76 12
[5,] 34 53
> rows <- c(1,1,2,3,3,4,5)
> cols <- c(1,2,2,1,2,1,2)
magic
> x
[,1] [,2]
[1,] 65 345
[2,] 0 65
[3,] 52 87
[4,] 76 0
[5,] 0 53
许多感谢。