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ggplot2 layer-like objects

Source: R/layer-.R
layer-like.Rd

For technical reasons related to how ggplot2 implements layers, there is no single class from which all valid ggplot2 layers and lists of layers inherit. Thus, ggblend operations supports a variety of "layer-like" objects, documented here (see Details).

Usage

is_layer_like(x)

as_layer_like(x)

# S3 method for default
as_layer_like(x)

# S3 method for LayerInstance
as_layer_like(x)

# S3 method for list
as_layer_like(x)

# S3 method for layer_list
as_layer_like(x)

Arguments

x

A layer-like object. See Details.

Value

For is_layer_like(), a logical: TRUE if x is layer-like, FALSE otherwise.

For as_layer_like(), a "LayerInstance" or a layer_list().

Details

ggblend operations can be applied to several ggplot2::layer()-like objects, including:

  • objects of class "LayerInstance"; e.g. stats and geoms.

  • list()s of layer-like objects.

  • layer_list()s, which are a more type-safe version of list()s of layer-like objects.

Anywhere in ggblend where a function parameter is documented as being layer-like, it can be any of the above object types.

Functions

  • is_layer_like(): checks if an object is layer-like according to ggblend.

  • as_layer_like(): validates that an object is layer-like and converts it to a "LayerInstance" or layer_list().

Examples

library(ggplot2)

is_layer_like(geom_line())
#> [1] TRUE
is_layer_like(list(geom_line()))
#> [1] TRUE
is_layer_like(list(geom_line(), scale_x_continuous()))
#> [1] TRUE
is_layer_like(list(geom_line(), "abc"))
#> [1] FALSE