R Programming Language Certification Data Visualization & Graphics in R 1

Question 1

Which R package is most widely used for creating advanced data visualizations based on the Grammar of Graphics?

Accepted Answer

ggplot2

Answer

ggplot2, created by Hadley Wickham, implements the Grammar of Graphics and is the most popular R visualization package.

Question 2

In ggplot2, which function is used to add a scatter plot layer to a plot?

Accepted Answer

geom_point()

Answer

geom_point() adds a layer of points to a ggplot2 visualization, creating a scatter plot.

Question 3

What does the aes() function do in ggplot2?

Accepted Answer

Defines aesthetic mappings between data variables and visual properties

Answer

aes() (aesthetic mappings) maps data variables to visual properties like x, y, color, size, and shape.

Question 4

Which ggplot2 function is used to create separate panels for different subsets of data?

Accepted Answer

facet_wrap()

Answer

facet_wrap() creates a matrix of panels, each showing a different subset of the data defined by a categorical variable.

Question 5

In base R, which function saves a plot as a PNG file?

Accepted Answer

png()

Answer

png() opens a PNG graphics device; after drawing the plot, dev.off() closes and saves the file.

R Programming Language Certification Practice Test