ggplot2 (version 2.1.0)

theme: Set theme elements

Description

Use this function to modify theme settings.

Usage

theme(..., complete = FALSE, validate = TRUE)

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.

validate

TRUE to run validate_element, FALSE to bypass checks.

Theme elements

The individual theme elements are:

line

all line elements (element_line)

rect

all rectangular elements (element_rect)

text

all text elements (element_text)

title

all title elements: plot, axes, legends (element_text; inherits from text)

aspect.ratio

aspect ratio of the panel

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.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 ("none", "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")

legend.box.just

justification of each legend within the overall bounding box, when there are multiple legends ("top", "bottom", "left", or "right")

panel.background

background of plotting area, drawn underneath plot (element_rect; inherits from rect)

panel.border

border around plotting area, drawn on top of plot so that it covers tick marks and grid lines. This should be used with fill=NA (element_rect; inherits from rect)

panel.margin

margin around facet panels (unit)

panel.margin.x

horizontal margin around facet panels (unit; inherits from panel.margin)

panel.margin.y

vertical margin around facet panels (unit; inherits from panel.margin)

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)

panel.ontop

option to place the panel (background, gridlines) over the data layers. Usually used with a transparent or blank panel.background. (logical)

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 with the sizes of the top, right, bottom, and left margins)

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)

strip.switch.pad.grid

space between strips and axes when strips are switched (unit)

strip.switch.pad.wrap

space between strips and axes when strips are switched (unit)

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

element_blank

element_line

element_rect

element_text

Examples

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

# Scatter plot of gas mileage by vehicle weight
p <- ggplot(mtcars, aes(wt, 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 + labs(x = "Vehicle Weight", y = "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
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)) +
  geom_point(aes(colour = factor(cyl)))
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))
# Add a border to the whole legend
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.y = unit(0, "lines"))

# Put gridlines on top
meanprice <- tapply(diamonds$price, diamonds$cut, mean)
cut <- factor(levels(diamonds$cut), levels = levels(diamonds$cut))
df <- data.frame(meanprice, cut)
g <- ggplot(df, aes(cut, meanprice)) + geom_bar(stat = "identity")
g + geom_bar(stat = "identity") +
    theme(panel.background = element_blank(),
          panel.grid.major.x = element_blank(),
          panel.grid.minor.x = element_blank(),
          panel.grid.minor.y = element_blank(),
          panel.ontop = TRUE)

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