install.packages("class")
(x=pi*10^2)
class(x)
typeof(x)
class(cars)
typeof(cars)
names(cars)
summary(cars)
head(cars)
tail(cars)
str(cars)
row.names(cars)
attributes(cars)
class(dist~speed)
plot(dist~speed,cars)
plot(cars$speed,cars$dist)