set.seed(12)
sample(1:10)

sample(c(-1,1), 1)

steps.rw <- vector("numeric", length = 1000)
steps.rw

steps.rw[2] <- sample(c(-1,1), 1)
head(steps.rw)


steps.rw[3] <- steps.rw[2] + sample(c(-1,1), 1)
steps.rw[4] <- steps.rw[3] + sample(c(-1,1), 1)
steps.rw[5] <- steps.rw[4] + sample(c(-1,1), 1)
steps.rw[3] <- steps.rw[2] + sample(c(-1,1), 1)
steps.rw[3] <- steps.rw[2] + sample(c(-1,1), 1)
steps.rw[3] <- steps.rw[2] + sample(c(-1,1), 1)

steps.rw <- vector("numeric", length = 1000)
for(i in 2:1000)
{
  steps.rw[i] <- steps.rw[i-1] + sample(c(-1,1), 1)
}
steps.rw

plot(steps.rw, type = "l")

##tady delam funkci

random.walk <- function(no.steps)
{
  steps.rw <- vector("numeric", length = no.steps)
  for(i in 2:no.steps)
  {
    steps.rw[i] <- steps.rw[i-1] + sample(c(-1,1), 1)
  }
  steps.rw
}


rw <- random.walk(no.steps = 2000)
plot(rw, type = "l")

par(mfrow=c(5,4), mar=rep(0.5,4))
for(k in 1:20)
{
  plot(random.walk(2000))
}