R Exercises | Programming Exercises for Finance in the R Language

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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