Lay out panels in a grid.
Usage
facet_grid(
facets,
margins = FALSE,
scales = "fixed",
space = "fixed",
shrink = TRUE,
labeller = "label_value",
as.table = TRUE,
switch = NULL,
drop = TRUE
)
Arguments
- facets
a formula with the rows (of the tabular display) on the LHS and the columns (of the tabular display) on the RHS; the dot in the formula is used to indicate there should be no faceting on this dimension (either row or column). The formula can also be provided as a string instead of a classical formula object
- margins
either a logical value or a character vector. Margins are additional facets which contain all the data for each of the possible values of the faceting variables. If
FALSE
, no additional facets are included (the default). IfTRUE
, margins are included for all faceting variables. If specified as a character vector, it is the names of variables for which margins are to be created.- scales
Are scales shared across all facets (the default,
"fixed"
), or do they vary across rows ("free_x"
), columns ("free_y"
), or both rows and columns ("free"
)- space
If
"fixed"
, the default, all panels have the same size. If"free_y"
their height will be proportional to the length of the y scale; if"free_x"
their width will be proportional to the length of the x scale; or if"free"
both height and width will vary. This setting has no effect unless the appropriate scales also vary.- shrink
If
TRUE
, will shrink scales to fit output of statistics, not raw data. IfFALSE
, will be range of raw data before statistical summary.- labeller
A function that takes one data frame of labels and returns a list or data frame of character vectors. Each input column corresponds to one factor. Thus there will be more than one with formulae of the type
~cyl + am
. Each output column gets displayed as one separate line in the strip label. This function should inherit from the "labeller" S3 class for compatibility withlabeller()
. Seelabel_value
for more details and pointers to other options.- as.table
If
TRUE
, the default, the facets are laid out like a table with highest values at the bottom-right. IfFALSE
, the facets are laid out like a plot with the highest value at the top-right.- switch
By default, the labels are displayed on the top and right of the plot. If
"x"
, the top labels will be displayed to the bottom. If"y"
, the right-hand side labels will be displayed to the left. Can also be set to"both"
.- drop
If
TRUE
, the default, all factor levels not used in the data will automatically be dropped. IfFALSE
, all factor levels will be shown, regardless of whether or not they appear in the data.
Examples
p <- ggplot(mpg, aes(displ, cty)) + geom_point()
p + facet_grid(. ~ cyl)
p + facet_grid(drv ~ .)
p + facet_grid(drv ~ cyl)
# To change plot order of facet grid,
# change the order of variable levels with factor()
# If you combine a facetted dataset with a dataset that lacks those
# facetting variables, the data will be repeated across the missing
# combinations:
df <- data.frame(displ = mean(mpg$displ), cty = mean(mpg$cty))
p +
facet_grid(. ~ cyl) +
geom_point(data = df, colour = "red", size = 2)
# Free scales -------------------------------------------------------
# You can also choose whether the scales should be constant
# across all panels (the default), or whether they should be allowed
# to vary
mt <- ggplot(mtcars, aes(mpg, wt, colour = factor(cyl))) +
geom_point()
mt + facet_grid(. ~ cyl, scales = "free")
# If scales and space are free, then the mapping between position
# and values in the data will be the same across all panels. This
# is particularly useful for categorical axes
ggplot(mpg, aes(drv, model)) +
geom_point() +
facet_grid(manufacturer ~ ., scales = "free", space = "free") +
theme(strip.text.y = element_text(angle = 0))
# Facet labels ------------------------------------------------------
p <- ggplot(mtcars, aes(wt, mpg)) + geom_point()
p
# label_both() displays both variable name and value
p + facet_grid(vs ~ cyl, labeller = label_both)
# label_parsed() parses text into mathematical expressions, see ?plotmath
mtcars$cyl2 <- factor(mtcars$cyl, labels = c("alpha", "beta", "sqrt(x, y)"))
ggplot(mtcars, aes(wt, mpg)) +
geom_point() +
facet_grid(. ~ cyl2, labeller = label_parsed)
# label_bquote() makes it easy to construct math expressions
p + facet_grid(. ~ vs, labeller = label_bquote(cols = alpha ^ .(vs)))
# The facet strips can be displayed near the axes with switch
data <- transform(mtcars,
am = factor(am, levels = 0:1, c("Automatic", "Manual")),
gear = factor(gear, levels = 3:5, labels = c("Three", "Four", "Five"))
)
p <- ggplot(data, aes(mpg, disp)) + geom_point()
p + facet_grid(am ~ gear, switch = "both")
# It looks better without boxes around the strips
p + facet_grid(am ~ gear, switch = "both") +
theme(strip.background = element_blank())
# Margins ----------------------------------------------------------
# \donttest{
# Margins can be specified by logically (all yes or all no) or by specific
# variables as (character) variable names
mg <- ggplot(mtcars, aes(x = mpg, y = wt)) + geom_point()
mg + facet_grid(vs + am ~ gear)
mg + facet_grid(vs + am ~ gear, margins = TRUE)
mg + facet_grid(vs + am ~ gear, margins = "am")
# when margins are made over "vs", since the facets for "am" vary
# within the values of "vs", the marginal facet for "vs" is also
# a margin over "am".
mg + facet_grid(vs + am ~ gear, margins = "vs")
mg + facet_grid(vs + am ~ gear, margins = "gear")
mg + facet_grid(vs + am ~ gear, margins = c("gear", "am"))
# }