Introduction to R: Exercises
5. Functions. The base R distribution comes with many functions, such as mean() and sd(), which compute the
mean and standard deviation of a collection of numbers.
You are given a vector of stock returns named returns. Use the aforementioned functions to compute its mean and standard deviation.
returns <- c(1.11, 2.51, -1.01, 3.94, -5.44, -10.10)
# Compute the mean of the returns vector.
mean_return <- ___(returns)
# Compute the standard deviation of the returns vector.
std_return <- sd(___)
# Print the mean and standard deviation.
print(mean_return)
___(___)
# Compute the mean of the returns vector.
mean_return <- mean(returns)
# Compute the standard deviation of the returns vector.
sd_return <- sd(returns)
# Print the mean and standard deviation.
print(mean_return)
print(sd_return)
test_error()
test_object("mean_return", incorrect_msg="Did you use the `mean()` function?")
test_object("sd_return", incorrect_msg="Did you use `returns` as the argument to `sd()`?")
test_output_contains("print(mean_return)", incorrect_msg="Did you remember to print `mean_return`?")
test_output_contains("print(std_return)", incorrect_msg="Did you remember to print `std_return`?")
success_msg("Excellent work! Notice that `mean()` and `sd()` are part of the base package for `R`.")
Did you apply the `mean()` and `sd()` functions?
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