Working with comparisons will make your data analytical life easier. Instead of selecting a subset of days to investigate yourself (like before), you can simply ask R to return only those days where you realized a positive return for poker.
In the previous exercises you used selection_vector <- poker_vector > 0 to find the days on which you had a positive poker return. Now, you would like to know not only the days on which you won, but also how much you won on those days.
You can select the desired elements, by putting selection_vector between the square brackets that follow poker_vector:
poker_vector[selection_vector]
R knows what to do when you pass a logical vector in square brackets: it will only select the elements that correspond to TRUE in selection_vector.
Use selection_vector in square brackets to assign the amounts that you won on the profitable days to the variable poker_winning_days.
# Poker and roulette winnings from Monday to Friday:
poker_vector <- c(140, -50, 20, -120, 240)
roulette_vector <- c(-24, -50, 100, -350, 10)
days_vector <- c("Monday", "Tuesday", "Wednesday", "Thursday", "Friday")
names(poker_vector) <- days_vector
names(roulette_vector) <- days_vector
# Which days did you make money on poker?
selection_vector <- poker_vector > 0
# Select from poker_vector these days
poker_winning_days <-
# Poker and roulette winnings from Monday to Friday:
poker_vector <- c(140, -50, 20, -120, 240)
roulette_vector <- c(-24, -50, 100, -350, 10)
days_vector <- c("Monday", "Tuesday", "Wednesday", "Thursday", "Friday")
names(poker_vector) <- days_vector
names(roulette_vector) <- days_vector
# Which days did you make money on poker?
selection_vector <- poker_vector > 0
# Select from poker_vector these days
poker_winning_days <- poker_vector[selection_vector]
msg = "Do not change anything about the definition and naming of `poker_vector` and `roulette_vector`."
test_object("days_vector", undefined_msg = msg, incorrect_msg = msg)
test_object("poker_vector", eq_condition = "equal", undefined_msg = msg, incorrect_msg = msg)
test_object("roulette_vector", eq_condition = "equal", undefined_msg = msg, incorrect_msg = msg)
test_object("selection_vector", incorrect_msg = "Don't change the way `selection_vector` is calculated.")
test_object("poker_winning_days",
incorrect_msg = "It looks like `poker_winning_days` does not contain the correct result. Use `poker_vector[selection_vector]`.")
success_msg("Good job! Continue to the next exercise.")
Use poker_vector[selection_vector] to select the desired elements from poker_vector, and assign the result to poker_winning_days.