uses_geom_params: Does a layer use one of more specific parameters?

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

Does a layer use one of more specific parameters?

Description

uses_geom_params checks that a plot's geom layer uses a specific parameter.

Usage

uses_geom_params(p, geom, ..., params = NULL, i = NULL)

uses_geom_param(p, geom, ..., params = NULL, i = NULL)

Arguments

p	A ggplot object
geom	A character string found in the suffix of a ggplot2 geom function, e.g. "point".
...	<dynamic-dots> Named values or character strings. Unnamed arguments will check whether any value was set for that parameter. Named arguments will check whether the parameter with the same name has a matching value. Each argument should have a name matching a ggplot layer parameter. Values may be passed as arguments or as list elements.
params	A named list of geom or stat parameter values, e.g. list(outlier.alpha = 0.01). This list is combined with any inputs to ...
i	A numerical index, e.g. 1.

Details

To specify a specific geom layer, either specify using position using the i index or by using a combination of geom function suffix name and i to check the ith layer that uses the geom.

The params argument accepts a list that contains geom, stat, or aes parameters. This offers flexibility in certain situations where setting a parameter on a geom_ function is actually setting a stat parameter or aes parameter. For example, in geom_histogram(binwidth = 500), the binwidth is a stat parameter, while in geom_histogram(fill = "blue"), the fill is an aes parameter. uses_geom_params will take this into account and check geom, stat, and aes parameters.

Note that uses_geom_params() can detect aes parameters, but not aes mappings. Parameters are set to static values directly within a layer (e.g. geom_point(color = "blue")), while mappings associate variables in the data with plot aesthetics using aes() (e.g. geom_point(aes(color = class))).

Value

A named logical vector of the same length as the number of inputs to ....

See Also

Other functions for checking geom parameters: get_default_params()

Examples

require(ggplot2)

p <- ggplot(data = diamonds, aes(x = cut, y = price)) +
  geom_boxplot(varwidth = TRUE, outlier.alpha = 0.01, fill = "blue")

uses_geom_params(
  p, "boxplot", list(varwidth = TRUE, outlier.alpha = 0.01, fill = "blue")
)

uses_geom_params(
  p, "boxplot", varwidth = TRUE, outlier.alpha = 0.01, fill = "blue"
)

# Unnamed arguments check that a parameter is set to any value
uses_geom_params(p, "boxplot", "fill")

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