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Check if an object is a ggplot

Source: R/is_ggplot.R
is_ggplot.Rd

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 ggplotobject; 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)
#> [1] TRUE
stop_if_not_ggplot(p_valid)
fail_if_not_ggplot(p_valid)

p_invalid <- geom_point()
is_ggplot(p_invalid)
#> [1] FALSE
if (FALSE) {
stop_if_not_ggplot(p_invalid)
}
fail_if_not_ggplot(p_valid)