Combine two pmx theme elements

Overlay one pmx_element onto another of the same subclass. Each set field in b overrides the matching field in a; fields unique to a are unchanged. Useful for layering partial overrides on a base element: pmx_point(size = 2) + pmx_point(color = "red") returns pmx_point(size = 2, color = "red").

Cross-subclass combinations (e.g. pmx_style + pmx_point) are intentionally disallowed — pmx_style is a theme-level shortcut applied at theme construction time, not a sibling element type.

Usage

# S3 method for class 'pmx_element'
a + b

Arguments

a

A pmx_element object (left side, the "base").

b

A pmx_element object of the same subclass as a (right side, the "override"), or NULL. When NULL, a is returned unchanged.

Value

A pmx_element with the same class as a.

Examples

pmx_point(size = 2) + pmx_point(color = "red")
#> <pmx_point>
#>   size = 2, color = red
pmx_line(linewidth = 1) + NULL
#> <pmx_line>
#>   linewidth = 1