By making use of comparison operators, we can approach the previous question in a more proactive way.
The (logical) comparison operators known to R are:
< for less than> for greater than<= for less than or equal to>= for greater than or equal to== for equal to each other!= not equal to each otherAs seen in the previous chapter, stating 6 > 5 returns TRUE. The nice thing about R is that you can use these comparison operators also on vectors. For example:
> c(4, 5, 6) > 5
[1] FALSE FALSE TRUE
This command tests for every element of the vector if the condition stated by the comparison operator is TRUE or FALSE.
poker_vector are positive (i.e. > 0) and assign this to selection_vector. selection_vector so you can inspect it. The printout tells you whether you won (TRUE) or lost (FALSE) any money for each day.
# 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 <-
# Print out selection_vector
# 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
# Print out selection_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 = "It looks like `selection_vector` does not contain the correct result. Remember that R uses element wise operations for vectors.")
test_output_contains("selection_vector", incorrect_msg = "Don't forget to print out `selection_vector` by writing the variable name on a new line.")
success_msg("Great!")
In order to check for which days your poker gains are positive, R should check for each element of poker_vector whether it is larger than zero. some_vector > 0 is the way to tell R what you are after.