现代统计图形 - 科学网—博客

152 附录 A 程序初步
1 > # 冒号表示步长为1或-1的序列
2 > 10:1
[1] 10 9 8 7 6 5 4 3 2 1
1 > # 步长为0.2
2 > seq(7, 9, 0.2)
[1] 7.0 7.2 7.4 7.6 7.8 8.0 8.2 8.4 8.6 8.8 9.0
1 > # 生成向量长度为6
2 > seq(7, 9, length.out = 6)
[1] 7.0 7.4 7.8 8.2 8.6 9.0
1 > rep(2, 10)
[1] 2 2 2 2 2 2 2 2 2 2
1 > # 整个向量重复5次
2 > rep(1:3, 5)
[1] 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3
1 > # 每个元素重复5次
2 > rep(1:3, each = 5)
[1] 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3
1 > # 每个元素分别重复1、2、3次
2 > rep(1:3, 1:3)
[1] 1 2 2 3 3 3
向量除了可以是数值型之外,还可以是逻辑值、字符等,如:
1 > (z = (x < 5))
A B C D
FALSE FALSE FALSE TRUE
1 > # letters和LETTERS是R中的字符常量
2 > letters
[1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o"
[16] "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z"