Instructions
- Problem sets for the individual exercise is in below. You can also access the code
here
- Upload your individual exercise to your
GitHub repo by Sun 11:59pm.
- I will upload an answer key later
# # 1. Functions ------------------------------------------------------------
#
#
# # What is a function that displays all the objects currently stored in
# # the memory? Write it below after deleting the line that reads
# # "WRITE YOUR ANSWER (code) HERE", and execute it.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Create a new object named x5 that is a number 100.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Calculate the square root of x5 using the sqrt() function
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Calculate the square root of x5 by raising it to the power of 0.5.
# # Your numeric answer should be exactly the same as when you used the
# # sqrt() function. This is because taking the sqaure root of something
# # is equivalent to raising it to the power of 0.5.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Create an object called x6 that is equal to 31.8734.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Use the round() function to get the value of x6 rounded off to
# # three decimal places
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Functions floor() and ceiling() can also be used to trim a number
# # down to an integer: apply both of these functions to x6 and compare
# # the outputs. Can you guess what these functions do?
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# WRITE YOUR ANSWER (comments) HERE
#
#
# # To find out if your hunch was right, refer to the help file of these
# # functions. Write a code to open up the help file for the floor function.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # 2. Vectors --------------------------------------------------------------
#
#
# # Create an object called "vec.a" which is a vector consisting of
# # the numbers, 1, 3, 5, 7. You need to use the c function.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Create a vector called "vec.b" consisting of the numbers, 2, 4, 6, 8.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Subtract vec.b from vec.a
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Create a new vector called vec.c by multiplying vec.a by vector vec.b
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Create a new vector called vec.d by taking the square root of each
# # member of vec.c
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # What is the third element of the vec.d vector? Find out using
# # square bracket. Note that since this is a vector, you only need to
# # provide a single number inside the brackets.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # Create a new vector called vec.e consisting of all the integers
# # from 1 through 100. You should use the seq function, rather than writing
# # down all the 100 integers individually.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # The mean function calculates the arithmetic mean of the numbers stored
# # in an object. Using the mean function, calculate the mean of the vec.e vector.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # As we saw in the joint exercise, the sum function calculates the sum of all
# # the elements in an object. Calculate the sum of the vec.e vector.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # The length function returns the number of elements stored in an object.
# # Using the length function, find the number of elements stored in the vec.e
# # vector.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # The mean of an object can be obtained by sum(X)/length(X) because
# # the defininition of the mean is the sum of elements divided by the number of
# # elements. Now, using the sum and length functions, calculate the mean of
# # the vec.e vector. Compare the answer with that obtained with the mean function
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # We have learned that the by argument specifies an increment. For example,
#
#
# seq(from = 0, to = 10, by = 2)
#
#
# # This creates a sequence that starts from 0 and ends with 10, and with
# # an increment of 2.
#
#
#
#
# # Now, create a new object called olympic which is a sequence that
# # starts from 1896 and ends with 2012, with an increment of 4.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # How many elements does the olympic vector contain? That is, what is
# # the length of this vector? Find out by applying a function (not by
# # manually counting the number of elements).
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # So there are 30 elements in the olympic vector. Display all the
# # elements contained in the olympic vector. These are the years
# # where olympic games were (supposed to be) held. Display the
# # contents of the olympic vector.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Find out how many olympic games will have been held by the year
# # 2400. Use the length and seq functions.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # 3. Matrices -------------------------------------------------------------
#
#
# # Create a new vector called "v1" consisting of the following numbers:
# # 1, 3, 5, 7, 9, 11
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Find out the length of this vector (Don't count the numbers by hand;
# # use an appropriate function).
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # We will conver this vector into a matrix. That is, we will rearrange this
# # vector so that it will have two dimensions (rows and columns).
# # Since this vector has 6 numbers, if we want the matrix to have two
# # rows, how many columns will there be?
#
#
# WRITE YOUR ANSWER AS A COMMENT.
#
#
#
#
# # Create a matrix called mat.v using the following command:
# # matrix(data = v1, nrow = 2)
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
# # Take a look at the contens of this matrix.
# # How many columns are there?
#
#
#
#
# # Notice how the numbers in vec.v are used to fill up the cells of mat.v.
# # We can see that R did it "by column". That is, R first filled up the
# # first column of mat.v with the first two elements of vec.v, then moved
# # on to the second and third columns.
#
#
#
#
# # You can use the byrow argument to change this. This argument takes
# # one of two values, TRUE or FALSE (or T or F). That is, we write
# # matrix(data = v1, nrow = 2, byrow = TRUE)
# # Now, create an object called mat.w using the command above.
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # Compare mat.v and mat.w. Do you see that R filled up the cells
# # "by row" to create the mat.w matrix ?
#
#
# # Many functions in R have arguments that take TRUE or FALSE like
# # the byrow argument we just used. In most cases, functions have a
# # default value. In the case of the matrix function, the default
# # value for the byrow argument is FALSE, meaning that, if you don't
# # specify anything, R will automatically sets byrow = FALSE.
#
#
#
#
#
#
# # Find the number in the second row, second column of mat.w
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # Find the number in the second row, second column of mat.v
#
#
# WRITE YOUR ANSWER (code) HERE
#
#
#
#
# # Finally, execute the entire contents of this R file by pressing
# # Ctrl + A and then pressing Ctrl + Enter.
# # Make sure that you don't get any error message. If you get an
# # error message, it's probably because you forgot to comment out
# # something.
#
#
# # End of file