ggplot2 (version 2.1.0)

+.gg: Add a new component to a ggplot or theme object.

Description

This operator allows you to add objects to a ggplot or theme object.

Usage

"+"(e1, e2)
e1 %+% e2
e1 %+replace% e2

Arguments

e1

An object of class ggplot or theme

e2

A component to add to e1

Details

If the first object is an object of class ggplot, you can add the following types of objects, and it will return a modified ggplot object.

• data.frame: replace current data.frame (must use %+%)
• uneval: replace current aesthetics
• layer: add new layer
• theme: update plot theme
• scale: replace current scale
• coord: override current coordinate system
• facet: override current coordinate faceting

If the first object is an object of class theme, you can add another theme object. This will return a modified theme object.

For theme objects, the + operator and the %+replace% can be used to modify elements in themes.

The + operator updates the elements of e1 that differ from elements specified (not NULL) in e2. Thus this operator can be used to incrementally add or modify attributes of a ggplot theme.

In contrast, the %+replace% operator replaces the entire element; any element of a theme not specified in e2 will not be present in the resulting theme (i.e. NULL). Thus this operator can be used to overwrite an entire theme.

See Also

theme

Examples

### Adding objects to a ggplot object
p <- ggplot(mtcars, aes(wt, mpg, colour = disp)) +
  geom_point()

p
p + coord_cartesian(ylim = c(0, 40))
p + scale_colour_continuous(breaks = c(100, 300))
p + guides(colour = "colourbar")

# Use a different data frame
m <- mtcars[1:10, ]
p %+% m

### Adding objects to a theme object
# Compare these results of adding theme objects to other theme objects
add_el <- theme_grey() + theme(text = element_text(family = "Times"))
rep_el <- theme_grey() %+replace% theme(text = element_text(family = "Times"))

add_el$text
rep_el$text

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