demo(persp)
demo(graphics)
x <- 1
y <- 2
x*y -> z
x <- c(1,2,3)
x
y <- c(2,3,4)
x*y
z <- 9
x*z
a <- c(1,2)
x*a
length(x)
length(y)
length(z)
x <- c(1,2,3,4,5)
y <- c('1','2','3','4','5')
z <- c('how', 'are', 'u', '?')
str(x)
str(y)
str(z)
structure(z)
str(z)
1 + 2 == 3
2 + 5 == 4
x == y
x == z
x <- c(1,22,3,4,5,565,-7,123,4554,-66)
sum(x)
mean(x)
sum(x)/length(x)
max(x)
min(x)
y <- c(1:100)
x[1]
x[10]
y[10]
z <- c(3:15)
x[5]
x[5:10]
y[10:20]
sum(x[x>100]); # pandas 불리안 인덱싱과 비슷
which(x>100); # 100 보다 큰 값들이 어디 있는지 위치 알려줌