Ako sa naučiť analýzu

# uloha 6
set.seed(1234)
x <- rnorm(100, mean = 1, sd = 2)
y <- rnorm(100, mean = 1, sd = 2)
cor(x,y)
plot(y ~ x)

x = c(x, 10)
y = c(y, 20)
cor(x,y)
plot(y ~ x)


# uloha 7
set.seed(123)
x <- rnorm(100, mean = 1, sd = 2)
y <- rnorm(100, mean = 1, sd = 2)
cor(x,y)

y2 <- rnorm(100, mean = 1, sd = 1.5)
cor(x,y2)
hist(y2, freq=FALSE)
lines(density(y2))

y3 <- rnorm(100, mean = 1, sd = 1)
cor(x,y3)
hist(y3, freq=FALSE)
lines(density(y3))

y4 <- rnorm(100, mean = 1, sd = 0.5)
cor(x,y4)
hist(y4, freq=FALSE)
lines(density(y4))


# uloha 8
x <- seq(from = 0, to = 10, by = 0.5)
f <- function(x) { 2.5*x + 2 }
y <- sapply(x,f)

noise <- rnorm(length(y), mean = 0, sd = 0.5)
y <- y + noise
plot(y ~ x)

noise2 <- rnorm(length(y), mean = 0, sd = 1)
y <- y + noise2
plot(y ~ x)
cor(x,y)

noise3 <- rnorm(length(y), mean = 0, sd = 1.5)
y <- y + noise3
plot(y ~ x)
cor(x,y)

noise4 <- rnorm(length(y), mean = 0, sd = 2)
y <- y + noise4
plot(y ~ x)
cor(x,y)

noise5 <- rnorm(length(y), mean = 0, sd = 3)
y <- y + noise5
plot(y ~ x)
cor(x,y)


# uloha 9
x <- runif(100, min = 0, max = 10)
f <- function(x){ 2*sin(x) + x }
y <- sapply(x,f)

noise <- rnorm(length(y), mean = 0, sd = 0.1)
y <- y + noise
plot(y ~ x)
cor(x,y)

nerozumiem ?