x <- c(1, 2, 3)


c(1,2,3)#vytvarim vektor

x <- c(1, 2, 3)
length(x)
?length

length(x)
class(x)

y <- c("ahoj", "nazdar", "cau")

x <- 1:100000000

x <- seq(0, 100, 2)
length(x[seq(40,50)])

x*5
length(x)
x * c(1:50)

x[40:50][2:3][1]

m <- matrix(data = NA, nrow = 5, ncol = 4)
m
m <- matrix(data = 1:20, nrow = 5, ncol = 4)
m[,1]
m[2,]

head(x, 10)
head(m)
tail(x)

m[2:3,3]
m[c(2,5),3]

m * 10
m * 1:10

m[2:4,3] <- c(1000, 2000, 3000)
m
m[2,4] <- "ahoj"
m
m +1

df <- data.frame(prvni=c(1:4), druhy=letters[1:4], 
                 treti=c(TRUE, TRUE, FALSE, TRUE))
df
class(df[,3])

colnames(df)[2] <- "sloupec"
df

df[,2]
df$sloupec
df[1:2, "sloupec"]
df$sloupec[1:2]

m <- matrix(data = 1:20, nrow = 5, ncol = 5, byrow = F)
m
m * 1:5

m[,6] <- 1:5
df$ctvrty <- 1:4
df[,5] <- 1:4
df

l <- list(prvni=1, druhy=seq(2,8,2), treti=m)
l
l$treti[3,3]

l[[4]] <- c(TRUE, FALSE, TRUE)
l
l[2]
l$druhy
l[[2]][3]

l[[3]][3,3]