pausa <- function() { cat ("\n >> press Enter to continue\n"); scan() }

# extract the vectors of individuals variables

x1 <- as.vector(chain[[1]][,1])
x2 <- as.vector(chain[[1]][,2])
x3 <- as.vector(chain[[1]][,3])
x4 <- as.vector(chain[[1]][,4])
x5 <- as.vector(chain[[1]][,5])
x6 <- as.vector(chain[[1]][,6])

# barplot/hist for discrete/continuous variables
barplot(table(x1), col='cyan', xlab='x1')
pausa()
hist(x2, nc=50, col='cyan')
pausa()
barplot(table(x3), col='cyan', xlab='x3')
pausa()
hist(x4, nc=50, col='cyan')
pausa()
plot(x5, x6, col='blue')