gglmannotate annotates a ggplot2 with a description of a linear model.
Installation
Install the development version from GitHub:
devtools::install_github("wilkox/gglmannotate")
How to use
To add a description of a linear model to a scatter plot built with
ggplot2, just add geom_lmannotate().
library(ggplot2)
library(gglmannotate)
ggplot(mpg, aes(x = displ, y = hwy)) +
geom_point() +
geom_smooth(method = "lm") +
geom_lmannotate()
Grouping, for example by adding a colour aesthetic, is automatically handled.
ggplot(mpg, aes(x = displ, y = hwy, colour = class)) +
geom_point() +
geom_smooth(method = "lm") +
geom_lmannotate()
Faceting is also supported.
ggplot(mpg, aes(x = displ, y = hwy)) +
geom_point() +
geom_smooth(method = "lm") +
geom_lmannotate() +
facet_wrap(~ class)
Customising the annotation text
The annotation can be changed from the default by setting the glue_exp
argument to geom_lmannotate(), which will be parsed with the glue()
function from the glue package. This
allows interpolation of R variables and expressions. The linear model
object (the output of lm()) is available inside the glue expression as
the variable model. For example:
ggplot(mpg, aes(x = displ, y = hwy, colour = class)) +
geom_point() +
geom_smooth(method = "lm") +
geom_lmannotate(glue_exp = "Max residual: {signif(max(model$residuals), 2)}")
Customising the annotation placement
To change the region of the plot area in which annotations will be
drawn, use the region argument to geom_lmannotate(). It takes a
named numeric vector with elements ‘xmin’, ‘xmax’, ‘ymin’ and ‘ymax’,
all scaled between 0 and 1, to define the region.
The vertical and horizontal aliment of the text within the region can be
set with place. It accepts the following values: “right”,
“bottomright”, “bottom”, “bottomleft”, “left”, “topleft”, “top”, and
“centre|center|middle”.
ggplot(mpg, aes(x = hwy, y = cty, colour = class)) +
geom_point() +
geom_smooth(method = "lm") +
geom_lmannotate(
region = c(xmin = 0, xmax = 0.75, ymin = 0.75, ymax = 1),
place = "topleft"
)
The annotation text layout can be further tweaked with the min.size,
grow and reflow options. See the ggfittext
package for full details on these
options.