Table of Contents
Introduction to R Programming for Data Science Week 01 Quiz Answers
Q1. R can perform several forms of statistical computation. What is an example of hypothesis testing?
- Inferring an unknown mean value of a population from its samples.
- Compute and visualize a correlation matrix among four different variables to see if they are correlated.
- Obtaining a representative subset of data.
- Testing if the mean values of two groups are statistically different.
Q2. Which of the following data type conversions may be not allowed in R?
- integer (like 1L or 2L) to numeric
- character (like `1`, `A`, or `test`) to numeric
- logical (like TRUE or FALSE) to numeric
- numeric (like 1 or 2) to integer
Q3. What is the result of the R expression 100 * (5 – 3)?
Q4. After you write code in an R script file or the R Console, what component of the R environment parses the code into objects in memory?
- R Interpreter
- R variables, functions, and datasets
- R data files
- R Workspace
Q5. Which features of RStudio help facilitate code writing? Select two answers.
- Workspace visualization
- Syntax highlighting
- Code auto completion
- File Explorer
Q6. True or False: Execution order does not matter when executing cells in a Jupyter notebook
Introduction to R Programming for Data Science Week 02 Quiz Answers
Q1. What is a nominal factor?
- A factor with any type or number of elements.
- A factor with ordering.
- A factor with no implied order.
- A factor that contains numeric data.
Q2. Assume that the variable test_result contains the vector c(25, 35, 40, 50, 75).What is the result of the expression mean(test_result)?
Q3. Assume you have variable called employee that contains the expression list(name = “Juan”, age = 30). What is the correct command to change the contents of the age item to 35?
- employee[age] = 35
- employee[age] <- 35
- employee[“age”] == 35
- employee[“age”] <- 35
Q4. What is the main difference between a matrix and an array?
- A matrix can contain multiple types of data, but an array can only contain data of the same type.
- A matrix must be two-dimensional, but an array can be single, two-dimensional, or more than two-dimensional.
- A matrix can contain vectors, but an array can only contain strings, characters, or integers.
- A matrix can be arranged by rows or columns, but an array is always arranged by columns.
Q5. Assume that you have a data frame called employee that contains three variables: name, age, and title. If you want to return all the values in the title variable, what command should you use?
Introduction to R Programming for Data Science Week 03 Quiz Answers
Q1. What is the result of the conditional statement 25 > 15 | 99 >= 100?
Q2. How do you define a global variable in a function?
- Use the == assignment operator.
- Use the -> assignment operator.
- Use the <- assignment operator.
- Use the <<- assignment operator.
Q3. You can use the str_sub() function to form a substring by counting back from the last position. This function is part of which package?
Q4. Assume you have a data frame that contains a string variable called ‘phone’. The phone numbers in this variable appear in (###) ###-#### or ###-###-#### format. Which feature of R can you use to isolate the area code (the three numbers between the parentheses or the first three numbers)?
- It is not possible to do this using R.
- A regular expression.
- A mathematical operation.
- A string operation.
Q5. When you convert a date in string format to a Date object, what information do you need to pass to the as.Date() function? Select two answers.
- The number of days since January 1, 1970.
- The date format of the string.
- The UNIX format of the string.
- The string containing the date.
Q6. What is the difference between an error and a warning in your R code?
- An error halts code execution, while a warning does not.
- You can catch an error, but you cannot catch a warning.
- A warning halts code execution, while an error does not.
- You can catch a warning, but you cannot catch an error.
Introduction to R Programming for Data Science Week 04 Quiz Answers
Q1. Assume you have read a .csv file into a data frame variable called employee. It has 20 rows of data and three variables: name, age, and title. What is the correct statement to use to return the fifth row of data in the name and title columns?
- employee[5, 2:3]
- employee[c(“name”, “title”), 5]
- employee[2:3, 1:5]
- employee[5, c(“name”, “title”)]
Q2. How do you return the number of characters in each paragraph of a text file that has been read into a character vector?
- Use the nchar() function.
- Use the file.size() function.
- Use the scan() function.
- Use the length() function.
Q3. Which package do you need to install before writing to an Excel file in R?
- No package is needed. This functionality is built into R.
Q4. You want to get a resource by its URL using an HTTP request and assign the HTTP response containing status code, headers, response body to a response variable. Which function should you use?
- response <-POST(“https://www.mysite.com”)
- response <-HEAD(“https://www.mysite.com”)
- response <-PUT(“https://www.mysite.com”)
- response <- GET(“https://www.mysite.com”)
Q5. After reading an HTML page from a URL, what must you do to get the <body> node from the root <html> node?
- Use the html_node() function to return the <html> node.
- Use the html_text() function to return the <body> node of the HTML.
- Use the html_node() function to return the <body> as a child node of <html> node.
- Use the html_text() function to return the <html> node.