A.9 Very Basic Functions
다음은 R을 배울때 가장 먼저 배우는 함수들이다.
? # help
c # concatenate or combine vectors or lists
str # show the structure
install.packages # install packages from a repository
library # load package
require # load package with returning TRUE or FALSE
rep # repeat
seq # sequence
setwd # set working directory
getwd # get working directory
print # has some useful options
expression # expression constructor
attach # not recommended to use this function
detach # make the names no longer available or unload packages