现代统计图形 - 科学网—博客

A.1 对象类型 155
1 > # 3维数组示例
2 > (x = array(1:24, c(3, 4, 2)))
, , 1
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
, , 2
[,1] [,2] [,3] [,4]
[1,] 13 16 19 22
[2,] 14 17 20 23
[3,] 15 18 21 24
1 > # 维数
2 > dim(x)
[1] 3 4 2
1 > # 第3维第1个位置上的元
2 > x[, , 1]
[,1] [,2] [,3] [,4]
[1,] 1 4 7 10
[2,] 2 5 8 11
[3,] 3 6 9 12
1 > x[1, , 2]
[1] 13 16 19 22
1 > # 矩阵示例
2 > (x = matrix(1:12, nrow = 2, ncol = 6))
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] 1 3 5 7 9 11
[2,] 2 4 6 8 10 12
1 > x[1, 5]
[1] 9
1 > # 逻辑比较:是否小于5?
2 > x < 5