R Programming Language Certification Data Visualization & Reporting 2

Question 1

Which ggplot2 function modifies the overall appearance of a plot (background, gridlines, fonts)?

Accepted Answer

theme()

Answer

theme() controls non-data visual elements like background color, gridlines, axis text, legend position, and title fonts.

Question 2

What does coord_flip() do in ggplot2?

Accepted Answer

Swaps the x and y axes

Answer

coord_flip() swaps the x and y axes, which is commonly used to turn vertical bar charts into horizontal bar charts for better label readability.

Question 3

Which R Markdown output format produces an HTML document?

Accepted Answer

html_document

Answer

html_document in the YAML front matter of an R Markdown file renders the document as a self-contained HTML file viewable in a browser.

Question 4

Which function adds axis labels and a title to a ggplot2 plot?

Accepted Answer

labs()

Answer

labs() sets plot labels including title, subtitle, caption, and axis labels (x, y) in a single concise function call.

Question 5

Which ggplot2 geom creates a box plot?

Accepted Answer

geom_boxplot()

Answer

geom_boxplot() draws box plots showing the median, quartiles, and outliers for a continuous variable, optionally grouped by a categorical variable.

R Programming Language Certification Practice Test