使用vector函数可创建指定类型和长度的矢量
> vector("numeric",5) #等价于numeric(5)
[1] 0 0 0 0 0
> vector("complex",5) #等价于complex(5)
[1] 0+0i 0+0i 0+0i 0+0i 0+0i
> vector("logical",5) #等价于logical(5)
[1] FALSE FALSE FALSE FALSE FALSE
> vector("character",5) #等价于character(5)
[1] "" "" "" "" ""
> vector("list",5)
[[1]]
NULL
[[2]]
NULL
[[3]]
NULL
[[4]]
NULL
[[5]]
NULL
可通过seq来创建序列,seq.int(3,12)等价于3:12,该函数还有更为灵活的用法，除了指定序列的范围外还可指定步长
> seq.int(3,12,2) [1] 3 5 7 9 11
如上面示例所示，该序列包含3到12之间步长为2的数字。seq_along则创建一个从1开始，长度为输入值的序列
> p <- c("Piper", "Peter", "picked", "a", "peck", "of", "pickled", "peppers")
> for(i in seq_along(p)) print(p[i])
[1] "Piper"
[1] "Peter"
[1] "picked"
[1] "a"
[1] "peck"
[1] "of"
[1] "pickled"
[1] "peppers"
length()函数可查看向量的长度，nchar()函数可查看字符的长度
索引向量
> x <- (1:5)^2
> x
[1] 1 4 9 16 25
> x[c(1, 3 ,5)]
[1] 1 9 25
> x[c(-2, -4)]
[1] 1 9 25
> x[c(TRUE, FALSE, TRUE, FALSE, TRUE)]
[1] 1 9 25
> names(x) <- c("one", "four", "nine", "sixteen", "twenty five")
> x[c("one", "nine", "twenty five")]
one nine twenty five
1 9 25
> which(x > 10)
sixteen twenty five
4 5
> which.min(x)
one
1
> which.max(x)
twenty five
5
>
向量循环和重复
> rep(1:5, 3) [1] 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 > rep(1:5, each = 3) [1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 > rep(1:5, times = 1:5) [1] 1 2 2 3 3 3 4 4 4 4 5 5 5 5 5 > rep(1:5, length.out = 7) [1] 1 2 3 4 5 1 2 > rep.int(1:5, 3) [1] 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 > rep_len(1:5, 13) [1] 1 2 3 4 5 1 2 3 4 5 1 2 3
