R Programming Language Certification Data Visualization & Reporting

Question 1

Which R package is most widely used for creating layered, publication-quality graphics?

Accepted Answer

ggplot2

Answer

ggplot2 implements the Grammar of Graphics, allowing users to build complex, publication-quality plots by layering geometric objects and aesthetics.

Question 2

In ggplot2, which function adds a scatter plot layer to a plot?

Accepted Answer

geom_point()

Answer

geom_point() adds a layer of points to a ggplot2 chart, creating a scatter plot when mapped to x and y aesthetics.

Question 3

What does the aes() function define in ggplot2?

Accepted Answer

Aesthetic mappings between data variables and visual properties

Answer

aes() (aesthetics) maps data variables to visual properties like x/y position, color, size, and shape in a ggplot2 plot.

Question 4

Which ggplot2 function creates separate panels for subsets of data?

Accepted Answer

facet_wrap()

Answer

facet_wrap() creates a multi-panel plot by wrapping panels for each level of a categorical variable into a rectangular layout.

Question 5

In R Markdown, which chunk option prevents code from being displayed in the output?

Accepted Answer

echo=FALSE

Answer

echo=FALSE hides the code chunk from the rendered output while still executing it and showing any results or plots it produces.

R Programming Language Certification Practice Test