###Exercise 1###
exercise1 <- data.frame(sequence = 1:5, letters = c("A", "C", "T", "F", "P"),
                        liar = c(T, F, T, F, F))
exercise1$fourth <- c(1, 4, 5, 2, 11)
fifth <- c(2:6)
exercise1 <- cbind(exercise1, fifth)
exercise1_filtered <- subset(exercise1, fourth >  2)
exercise1_filtered <- exercise1[exercise1$fourth > 2, ]
exercise1$fourth <- exercise1$fourth + exercise1$sequence


###Exercise 2###
write.table(data1, "data3.txt", sep = "\t")


###Exercise 3###
fahrenheit_to_celsius <- function(fahrenheit) {
  celsius <- (fahrenheit - 32) * 5 / 9
  return(celsius)
} 

###Exercise 4###
data(iris)
plot(iris$Sepal.Length, iris$Sepal.Width, col = c("aquamarine", "pink", "orange")[iris$Species],
     pch = c(7, 21, 18)[iris$Species])