R 기초

3+23-4

## [1] 22

3+2

## [1] 5

5-2

## [1] 3

3*2;

## [1] 6

# c(),rep()
x<-c(1,10)
y<-c("apple","melon")
xy<-c(x,y)
xy

## [1] "1"     "10"    "apple" "melon"

1:5

## [1] 1 2 3 4 5

5:1

## [1] 5 4 3 2 1

seq(from=1, to=5, by=1)

## [1] 1 2 3 4 5

seq(1, 5, 1)

## [1] 1 2 3 4 5

seq(1,11,length=6)

## [1]  1  3  5  7  9 11

sequence(3)

## [1] 1 2 3

#반복
rep(c("a","b"),times=2)

## [1] "a" "b" "a" "b"

x<-c(1,2,3)
mode(x)

## [1] "numeric"

is.numeric(x)

## [1] TRUE

is.logical(x)

## [1] FALSE

is.character(x)

## [1] FALSE

length(x)

## [1] 3

#변수 : variable(통계학과), feature(머신러닝)

x<-c("a","b","c")
x[1]

## [1] "a"

x[-1]

## [1] "b" "c"

x[c(1,2)];

## [1] "a" "b"

x<-c(1,2,3)
y<-c(4,5,6)
x+y

## [1] 5 7 9

x*y

## [1]  4 10 18

x/y;

## [1] 0.25 0.40 0.50

x<-c(1,2,3)
y<-c(1,2,3,4,5,6)
x+y; #결과 : [1] 2 4 6 5 7 9(1,2,3이 한번 더 반복됨)

## [1] 2 4 6 5 7 9