hi<-paste("Hi", "Jack") #连上
hi
paste("jac","k", sep="--") #sep 用什么连接
paste(hi,"what's up?", sep=", ")
paste("1", 1:10, sep="-") #1-1 1-2 1-3....
a<-paste("the value of 'pi' is",pi,",endless!")
noquote(a) #不加引号
print(a,quote = FALSE) #不加引号
mtcars #自带数据
cars<-rownames(mtcars)
colnames(mtcars)
nchar(cars) #长度。字母个数
which.max(nchar(cars)) #第几个最长
cars[which.max(nchar(cars))]
library(stringr)
cars
str_count(cars,"O") #有几个“O"
sum(str_count(toupper(cars), "TOYOTA"))