> c("HELLO","WORLD")

[1] "HELLO" "WORLD"

> paste(c("hello","hi"),"world")

[1] "hello world" "hi world"   

> paste(c("hello","hi"),"world",sep="-")

[1] "hello-world" "hi-world"   

> paste(c("hello","hi"),"world",collapse="!")

[1] "hello world!hi world"

> paste0(c("hello","hi"),"world")     #paste0函数能去掉分隔符

[1] "helloworld" "hiworld"   

> x 

[1]  1  4  9 16 25

> toString(x)

[1] "1, 4, 9, 16, 25"

> toString(x,width=2)     #width表示限制字符长度

[1] "1,...."

> toupper("hello world!")

[1] "HELLO WORLD!"

> tolower("HELLO WORLD!")

[1] "hello world!"

> pow <- 1:3

> (power_of_e <- exp(pow))

[1]  2.718282  7.389056 20.085537

> formatC(power_of_e)

[1] "2.718" "7.389" "20.09"

> formatC(power_of_e,digits=3)    #保留三个数字

[1] "2.72" "7.39" "20.1"

> formatC(power_of_e,digits=3,width=10)    #在前面添加空格

[1] "      2.72" "      7.39" "      20.1"

> formatC(power_of_e,digits=3,format="e")    #科学计数法

[1] "2.718e+00" "7.389e+00" "2.009e+01"

> formatC(power_of_e,digits=3,flag="+")    +前面加上+

[1] "+2.72" "+7.39" "+20.1"

> sprintf("%s %d %e", "Euler‘s constant to the power",pow,power_of_e)

[1] "Euler‘s constant to the power 1 2.718282e+00"

[2] "Euler‘s constant to the power 2 7.389056e+00"

[3] "Euler‘s constant to the power 3 2.008554e+01"

> (heights <- data.frame(height_cm = c(153,181,150,172,165),gender = c("female","male","male","female","male")))

  height_cm gender

1       153 female

2       181   male

3       150   male

4       172 female

5       165   male

> class(heights$gender)

[1] "factor"

> heights$gender

[1] female male   male   female male  

Levels: female male    #female和male称为因子水平

> gender_char <- c("female","male","male","female","male")

> (gender_factor <- factor(gender_char))

[1] female male   male   female male  

Levels: female male