Coursera | R Programming

Week 1 Quiz >> R Programming

Week 1 Quiz >> R Programming

1. R was developed by statisticians working at

  • Microsoft
  • Johns Hopkins University
  • The University of Auckland
  • Harvard University

2. The definition of free software consists of four freedoms (freedoms 0 through 3). Which of the following is NOT one of the freedoms that are part of the definition? Select all that apply.

  • The freedom to run the program, for any purpose.
  • The freedom to redistribute copies so you can help your neighbor.
  • The freedom to prevent users from using the software for undesirable purposes.
  • The freedom to improve the program, and release your improvements to the public, so that the whole community benefits.
  • The freedom to sell the software for any price.
  • The freedom to restrict access to the source code for the software.
  • The freedom to study how the program works, and adapt it to your needs.

3. In R the following are all atomic data types EXCEPT: (Select all that apply)

  • matrix
  • complex
  • data frame
  • table
  • list
  • array
  • numeric
  • logical
  • character
  • integer

4. If I execute the expression x <- 4L in R, what is the class of the object `x’ as determined by the `class()’ function?

  • character
  • complex
  • numeric
  • integer
  • matrix
  • logical

5. What is the class of the object defined by x <- c(4, TRUE)?

  • numeric
  • integer
  • matrix
  • list
  • character
  • logical

6. If I have two vectors x <- c(1,3, 5) and y <- c(3, 2, 10), what is produced by the expression cbind(x, y)?

  • a matrix with 2 columns and 3 rows
  • a 2 by 3 matrix
  • a vector of length 2
  • a 2 by 2 matrix
  • a vector of length 3
  • a 3 by 3 matrix

7. A key property of vectors in R is that

  • a vector cannot have have attributes like dimensions
  • elements of a vector all must be of the same class
  • elements of a vector can be of different classes
  • the length of a vector must be less than 32,768
  • elements of a vector can only be character or numeric

8. Suppose I have a list defined as x <- list(2, “a”, “b”, TRUE). What does x[[1]] give me? Select all that apply.

  • a numeric vector of length 1.
  • a list containing the number 2.
  • a character vector containing the element “2”.
  • a list containing the letter “a”.
  • a numeric vector containing the element 2.

9. Suppose I have a vector x <- 1:4 and a vector y <- 2. What is produced by the expression x + y?

  • an integer vector with elements 3, 2, 3, 6.
  • a numeric vector with elements 3, 2, 3, 4.
  • an integer vector with elements 3, 2, 3, 4.
  • a numeric vector with elements 3, 4, 5, 6.
  • a numeric vector with elements 3, 2, 3, 6.
  • a numeric vector with elements 1, 2, 3, 6.

10. Suppose I have a vector x <- c(17, 14, 4, 5, 13, 12, 10) and I want to set all elements of this vector that are greater than 10 to be equal to 4. What R code achieves this? Select all that apply.

  • x[x > 10] <- 4
  • x[x >= 10] <- 4
  • x[x >= 11] <- 4
  • x[x == 4] > 10
  • x[x == 10] <- 4
  • x[x < 10] <- 4
  • x[x > 4] <- 10
  • x[x > 10] == 4

11. Use the Week 1 Quiz Data Set to answer questions 11-20.
In the dataset provided for this Quiz, what are the column names of the dataset?

  • Month, Day, Temp, Wind
  • Ozone, Solar.R, Wind
  • Ozone, Solar.R, Wind, Temp, Month, Day
  • 1, 2, 3, 4, 5, 6

12. Extract the first 2 rows of the data frame and print them to the console. What does the output look like?

Ozone Solar.R Wind Temp Month Day
1    18     224 13.8   67     9  17
2    NA     258  9.7   81     7  22
Ozone Solar.R Wind Temp Month Day
1     9      24 10.9   71     9  14
2    18     131  8.0   76     9  29
✅ Ozone Solar.R Wind Temp Month Day
1    41     190  7.4   67     5   1
2    36     118  8.0   72     5   2
Ozone Solar.R Wind Temp Month Day
1     7      NA  6.9   74     5  11
2    35     274 10.3   82     7  17




13. How many observations (i.e. rows) are in this data frame?

  • 129
  • 160
  • 45
  • 153

14. Extract the last 2 rows of the data frame and print them to the console. What does the output look like?

Ozone Solar.R Wind Temp Month Day
152    31     244 10.9   78     8  19
153    29     127  9.7   82     6   7
✅ Ozone Solar.R Wind Temp Month Day
152    18     131  8.0   76     9  29
153    20     223 11.5   68     9  30
Ozone Solar.R Wind Temp Month Day
152    34     307 12.0   66     5  17
153    13      27 10.3   76     9  18
Ozone Solar.R Wind Temp Month Day
152    11      44  9.7   62     5  20
153   108     223  8.0   85     7  25





15. What is the value of Ozone in the 47th row?

  • 18
  • 34
  • 21
  • 63

16. How many missing values are in the Ozone column of this data frame?

  • 78
  • 9
  • 37
  • 43

17. What is the mean of the Ozone column in this dataset? Exclude missing values (coded as NA) from this calculation.

  • 53.2
  • 31.5
  • 42.1
  • 18.0

18. Extract the subset of rows of the data frame where Ozone values are above 31 and Temp values are above 90. What is the mean of Solar.R in this subset?

  • 334.0
  • 185.9
  • 205.0
  • 212.8

19. What is the mean of “Temp” when “Month” is equal to 6?

  • 75.3
  • 90.2
  • 79.1
  • 85.6

20. What was the maximum ozone value in the month of May (i.e. Month is equal to 5)?

  • 100
  • 18
  • 97
  • 115

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