is_ggplot: Check if an object is a ggplot

In rstudio-education/ggcheck: Inspect 'ggplot2' Plots for Automated Grading in Learning Exercises

Check if an object is a ggplot

Description

is_ggplot() tests if an object is a ggplot.

stop_if_not_ggplot() signals an error if an object is not a ggplot.

fail_if_not_ggplot() returns a failing grade if an object is not a ggplot.

Usage

is_ggplot(p)

stop_if_not_ggplot(p, message = getOption("ggcheck.error"))

fail_if_not_ggplot(
  p = .result,
  message = getOption("ggcheck.fail"),
  env = parent.frame()
)

Arguments

p	An object
message	A message to be displayed if p is not a ggplot object.
env	Environment in which to find .result. Most users of ggcheck will not need to use this argument.

Value

is_ggplot() returns TRUE if p is a ggplot object; otherwise it returns FALSE.

stop_if_not_ggplot() returns an error if p is not a ggplot object; other it invisibly returns NULL.

fail_if_not_ggplot() returns a failing grade if p is not a ggplot object; other it invisibly returns NULL.

Examples

require(ggplot2)

p_valid <- ggplot(data = mpg, mapping = aes(x = displ, y = hwy)) +
  geom_point()
is_ggplot(p_valid)
stop_if_not_ggplot(p_valid)
fail_if_not_ggplot(p_valid)

p_invalid <- geom_point()
is_ggplot(p_invalid)
## Not run: 
stop_if_not_ggplot(p_invalid)

## End(Not run)
fail_if_not_ggplot(p_valid)

rstudio-education/ggcheck documentation built on May 12, 2023, 11:33 a.m.