ggplot2 (version 0.9.2.1)

theme: Set theme elements

Description

Use this function to modify theme settings.

Usage

theme(..., complete = FALSE)

Arguments

...

a list of element name, element pairings that modify the existing theme.

complete

set this to TRUE if this is a complete theme, such as the one returned by theme_grey(). Complete themes behave differently when added to a ggplot object.

Theme elements

The individual theme elements are:

ll{ line all line elements (element_line) rect all rectangluar elements (element_rect) text all text elements (element_text) title all title elements: plot, axes, legends (element_text; inherits from text) axis.title label of axes (element_text; inherits from text) axis.title.x x axis label (element_text; inherits from axis.title) axis.title.y y axis label (element_text; inherits from axis.title) axis.text tick labels along axes (element_text; inherits from text) axis.text.x x axis tick labels (element_text; inherits from axis.text) axis.text.y y axis tick labels (element_text; inherits from axis.text) axis.ticks tick marks along axes (element_line; inherits from line) axis.ticks.x x axis tick marks (element_line; inherits from axis.ticks) axis.ticks.y y axis tick marks (element_line; inherits from axis.ticks) axis.ticks.length length of tick marks (unit) axis.ticks.margin space between tick mark and tick label (unit) axis.line lines along axes (element_line; inherits from line) axis.line.x line along x axis (element_line; inherits from axis.line) axis.line.y line along y axis (element_line; inherits from axis.line) legend.background background of legend (element_rect; inherits from rect) legend.margin extra space added around legend (unit) legend.key background underneath legend keys (element_rect; inherits from rect) legend.key.size size of legend keys (unit; inherits from legend.key.size) legend.key.height key background height (unit; inherits from legend.key.size) legend.key.width key background width (unit; inherits from legend.key.size) legend.text legend item labels (element_text; inherits from text) legend.text.align alignment of legend labels (number from 0 (left) to 1 (right)) legend.title title of legend (element_text; inherits from title) legend.title.align alignment of legend title (number from 0 (left) to 1 (right)) legend.position the position of legends. ("left", "right", "bottom", "top", or two-element numeric vector) legend.direction layout of items in legends ("horizontal" or "vertical") legend.justification anchor point for positioning legend inside plot ("center" or two-element numeric vector) legend.box arrangement of multiple legends ("horizontal" or "vertical") panel.background background of plotting area (element_rect; inherits from rect) panel.border border around plotting area (element_rect; inherits from rect) panel.margin margin around facet panels (unit) panel.grid grid lines (element_line; inherits from line) panel.grid.major major grid lines (element_line; inherits from panel.grid) panel.grid.minor minor grid lines (element_line; inherits from panel.grid) panel.grid.major.x vertical major grid lines (element_line; inherits from panel.grid.major) panel.grid.major.y horizontal major grid lines (element_line; inherits from panel.grid.major) panel.grid.minor.x vertical minor grid lines (element_line; inherits from panel.grid.minor) panel.grid.minor.y horizontal minor grid lines (element_line; inherits from panel.grid.minor) plot.background background of the entire plot (element_rect; inherits from rect) plot.title plot title (text appearance) (element_text; inherits from title) plot.margin margin around entire plot (unit) strip.background background of facet labels (element_rect; inherits from rect) strip.text facet labels (element_text; inherits from text) strip.text.x facet labels along horizontal direction (element_text; inherits from strip.text) strip.text.y facet labels along vertical direction (element_text; inherits from strip.text) }

Details

Theme elements can inherit properties from other theme elements. For example, axis.title.x inherits from axis.title, which in turn inherits from text. All text elements inherit directly or indirectly from text; all lines inherit from line, and all rectangular objects inherit from rect.

For more examples of modifying properties using inheritance, see +.gg and %+replace%.

To see a graphical representation of the inheritance tree, see the last example below.

See Also

+.gg

%+replace%

rel

Examples

p <- qplot(mpg, wt, data = mtcars)
p
p + theme(panel.background = element_rect(colour = "pink"))
p + theme_bw()

# Scatter plot of gas mileage by vehicle weight
p <- ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point()
# Calculate slope and intercept of line of best fit
coef(lm(mpg ~ wt, data = mtcars))
p + geom_abline(intercept = 37, slope = -5)
# Calculate correlation coefficient
with(mtcars, cor(wt, mpg, use = "everything", method = "pearson"))
#annotate the plot
p + geom_abline(intercept = 37, slope = -5) +
geom_text(data = data.frame(), aes(4.5, 30, label = "Pearson-R = -.87"))

# Change the axis labels
# Original plot
p
p + xlab("Vehicle Weight") + ylab("Miles per Gallon")
# Or
p + labs(x = "Vehicle Weight", y = "Miles per Gallon")

# Change title appearance
p <- p + labs(title = "Vehicle Weight-Gas Mileage Relationship")
# Set title to twice the base font size
p + theme(plot.title = element_text(size = rel(2)))
p + theme(plot.title = element_text(size = rel(2), colour = "blue"))

# Changing plot look with themes
DF <- data.frame(x = rnorm(400))
m <- ggplot(DF, aes(x = x)) + geom_histogram()
# Default is theme_grey()
m
# Compare with
m + theme_bw()

# Manipulate Axis Attributes
library(grid) # for unit
m + theme(axis.line = element_line(size = 3, colour = "red", linetype = "dotted"))
m + theme(axis.text = element_text(colour = "blue"))
m + theme(axis.text.y = element_blank())
m + theme(axis.ticks = element_line(size = 2))
m + theme(axis.title.y = element_text(size = rel(1.5), angle = 90))
m + theme(axis.title.x = element_blank())
m + theme(axis.ticks.length = unit(.85, "cm"))

# Legend Attributes
z <- ggplot(mtcars, aes(wt, mpg, colour = factor(cyl))) + geom_point()
z
z + theme(legend.position = "none")
z + theme(legend.position = "bottom")
# Or use relative coordinates between 0 and 1
z + theme(legend.position = c(.5, .5))
z + theme(legend.background = element_rect(colour = "black"))
# Legend margin controls extra space around outside of legend:
z + theme(legend.background = element_rect(), legend.margin = unit(1, "cm"))
z + theme(legend.background = element_rect(), legend.margin = unit(0, "cm"))
# Or to just the keys
z + theme(legend.key = element_rect(colour = "black"))
z + theme(legend.key = element_rect(fill = "yellow"))
z + theme(legend.key.size = unit(2.5, "cm"))
z + theme(legend.text = element_text(size = 20, colour = "red", angle = 45))
z + theme(legend.title = element_text(face = "italic"))

# To change the title of the legend use the name argument
# in one of the scale options
z + scale_colour_brewer(name = "My Legend")
z + scale_colour_grey(name = "Number of \nCylinders")

# Panel and Plot Attributes
z + theme(panel.background = element_rect(fill = "black"))
z + theme(panel.border = element_rect(linetype = "dashed", colour = "black"))
z + theme(panel.grid.major = element_line(colour = "blue"))
z + theme(panel.grid.minor = element_line(colour = "red", linetype = "dotted"))
z + theme(panel.grid.major = element_line(size = 2))
z + theme(panel.grid.major.y = element_blank(), panel.grid.minor.y = element_blank())
z + theme(plot.background = element_rect())
z + theme(plot.background = element_rect(fill = "green"))

# Faceting Attributes
set.seed(4940)
dsmall <- diamonds[sample(nrow(diamonds), 1000), ]
k <- ggplot(dsmall, aes(carat, ..density..)) + geom_histogram(binwidth = 0.2) +
facet_grid(. ~ cut)
k + theme(strip.background = element_rect(colour = "purple", fill = "pink",
                                          size = 3, linetype = "dashed"))
k + theme(strip.text.x = element_text(colour = "red", angle = 45, size = 10,
                                      hjust = 0.5, vjust = 0.5))
k + theme(panel.margin = unit(5, "lines"))
k + theme(panel.margin = unit(0, "lines"))


# Modify a theme and save it
mytheme <- theme_grey() + theme(plot.title = element_text(colour = "red"))
p + mytheme


## Run this to generate a graph of the element inheritance tree
build_element_graph <- function(tree) {
  require(igraph)
  require(plyr)

  inheritdf <- function(name, item) {
    if (length(item$inherit) == 0)
      data.frame()
    else
      data.frame(child = name, parent = item$inherit)
  }

  edges <- rbind.fill(mapply(inheritdf, names(tree), tree))

  # Explicitly add vertices (since not all are in edge list)
  vertices <- data.frame(name = names(tree))
  graph.data.frame(edges, vertices = vertices)
}

g <- build_element_graph(ggplot2:::.element_tree)
V(g)$label <- V(g)$name

set.seed(324)
par(mar=c(0,0,0,0)) # Remove unnecessary margins
plot(g, layout=layout.fruchterman.reingold, vertex.size=4, vertex.label.dist=.25)