date()
## [1] "Fri Sep 7 17:17:29 2012"
Due Date: September 13, 2012
Total Points: 30
1 The following values are the annual number hurricanes that have hit the United States since 1990. Follow instructions and answer questions by typing the appropriate R commands.
0 1 1 1 0 2 2 1 3 3 0 0 1 2 6 6 0 1 3 0 1
a. Enter the data into R. (2)
b. How many years are there? (2)
c. What is the total number of hurricanes over all years? (2)
(a) Enter the data into R. (2)
hurricanes = c(0, 1, 1, 1, 0, 2, 2, 1, 3, 3, 0, 0, 1, 2, 6, 6, 0, 1, 3, 0, 1)
(b) How many years are there? (2)
length(hurricanes)
## [1] 21
© What is the total number of hurricanes over all years? (2)
sum(hurricanes)
## [1] 34
2 Answer the following questions by typing the appropriate R commands.
a. Create a vector of numbers starting with 0 and ending with 25. (2)
b. What is the length of this vector? (2)
c. Create a new vector from the original vector by subtracting the mean value over all numbers in the vector. (2)
(a) Create a vector of numbers starting with 0 and ending with 25. (2)
numbers = c(0:25)
(b) What is the length of this vector? (2)
length(numbers)
## [1] 26
© Create a new vector from the original vector by subtracting the mean value over all numbers in the vector. (2)
numbers.MeanDiff = (numbers - mean(numbers))
numbers.MeanDiff
## [1] -12.5 -11.5 -10.5 -9.5 -8.5 -7.5 -6.5 -5.5 -4.5 -3.5 -2.5
## [12] -1.5 -0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5
## [23] 9.5 10.5 11.5 12.5
3 Suppose you keep track of your mileage each time you fill up. At your last 8 fill-ups the mileage was
65311 65624 65908 66219 66499 66821 67145 67447
a. Enter these numbers into a vector called miles. (2)
b. Use the function diff() to determine the number of miles between fill-ups. (2)
c. What is the maximum, minimum, and mean number of miles between fill-ups? (3)
(a) Enter these numbers into a vector called miles. (2)
miles = c(65311, 65624, 65908, 66219, 66499, 66821, 67145, 67447)
(b) Use the function diff() to determine the number of miles between fill-ups. (2)
diff(miles)
## [1] 313 284 311 280 322 324 302
© What is the maximum, minimum, and mean number of miles between fill-ups? (3)
max(diff(miles))
## [1] 324
min(diff(miles))
## [1] 280
mean(diff(miles))
## [1] 305.1
4 Create the following sequences using the seq() and rep() functions as appropriate.
a. “a”, “a”, “a”, “a” (2)
b. The odd numbers in the interval from 1 to 100 (2)
c. 1, 1, 1, 2, 2, 2, 3, 3, 3 (2)
d. 1, 1, 1, 2, 2, 3 (2)
e. 1, 2, 3, 4, 5, 4, 3, 2, 1 (3) Hint: Use the c() function.
(a) “a”, “a”, “a”, “a” (2)
rep("a", 4)
## [1] "a" "a" "a" "a"
(b) The odd numbers in the interval from 1 to 100 (2)
seq(1, 100, 2)
## [1] 1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45
## [24] 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91
## [47] 93 95 97 99
© 1, 1, 1, 2, 2, 2, 3, 3, 3 (2)
rep(c(1:3), c(3, 3, 3))
## [1] 1 1 1 2 2 2 3 3 3
(d) 1, 1, 1, 2, 2, 3 (2)
rep(c(1:3), c(3, 2, 1))
## [1] 1 1 1 2 2 3
(e) 1, 2, 3, 4, 5, 4, 3, 2, 1 (3) Hint: Use the c() function.
c(1:5, 4:1)
## [1] 1 2 3 4 5 4 3 2 1