R语言——rep()函数

# rep(x, …):将vector x的值循环n遍
rep(1:4, 2)
[1] 1 2 3 4 1 2 3 4

# times：整个数组循环几遍
rep(1:4, each = 2, times = 3)
[1] 1 1 2 2 3 3 4 4 1 1 2 2 3 3 4 4 1 1 2 2 3 3 4 4

# each：每个element循环几遍
rep(1:4, each = 2)
[1] 1 1 2 2 3 3 4 4
rep(1:4, c(2,2,2,2))
[1] 1 1 2 2 3 3 4 4
rep(1:4, c(2,1,2,1))
[1] 1 1 2 3 3 4

# length.out 输出长度为多少
rep(1:4, each = 2, len = 4)
[1] 1 1 2 2  #长了会被截掉

rep(1:4, each = 2, len = 13)
[1] 1 1 2 2 3 3 4 4 1 1 2 2 3  #短了会根据前面规则补上