R Programming Language Certification Data Visualization & Graphics in R 3

Question 1

Which base R function produces a histogram of a numeric vector?

Accepted Answer

hist()

Answer

hist() computes and displays a histogram of the values in a numeric vector using base R graphics.

Question 2

What does the labs() function do in ggplot2?

Accepted Answer

Sets axis labels, title, and legend titles

Answer

labs() is used to modify axis labels, the plot title, subtitle, caption, and legend labels in ggplot2.

Question 3

Which ggplot2 geom is used to create a box plot?

Accepted Answer

geom_boxplot()

Answer

geom_boxplot() draws box-and-whisker plots showing median, quartiles, and outliers for grouped data.

Question 4

Which R package provides the ColorBrewer palettes commonly used for categorical and sequential color scales in maps and charts?

Accepted Answer

RColorBrewer

Answer

RColorBrewer provides Cynthia Brewer's color palettes designed for sequential, diverging, and qualitative data.

Question 5

In ggplot2, which function sets fixed x and y axis limits on a plot?

Accepted Answer

xlim() and ylim()

Answer

xlim() and ylim() (or limits= inside scale_x/y_continuous()) set the visible range of each axis in ggplot2.

R Programming Language Certification Practice Test