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#' @include facet-.r
NULL
#' Lay out panels in a grid
#'
#' `facet_grid` forms a matrix of panels defined by row and column
#' facetting variables. It is most useful when you have two discrete
#' variables, and all combinations of the variables exist in the data.
#'
#' @param 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
#' @param 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). If `TRUE`, 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.
#' @param 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"`)
#' @param 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.
#' @param 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 with [labeller()]. See
#' [label_value()] for more details and pointers to other
#' options.
#' @param as.table If `TRUE`, the default, the facets are laid out like
#' a table with highest values at the bottom-right. If `FALSE`, the
#' facets are laid out like a plot with the highest value at the top-right.
#' @param 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"`.
#' @param shrink If `TRUE`, will shrink scales to fit output of
#' statistics, not raw data. If `FALSE`, will be range of raw data
#' before statistical summary.
#' @param drop If `TRUE`, the default, all factor levels not used in the
#' data will automatically be dropped. If `FALSE`, all factor levels
#' will be shown, regardless of whether or not they appear in the data.
#' @export
#' @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"))
#' }
#' @importFrom plyr as.quoted
facet_grid <- function(facets, margins = FALSE, scales = "fixed", space = "fixed", shrink = TRUE, labeller = "label_value", as.table = TRUE, switch = NULL, drop = TRUE) {
scales <- match.arg(scales, c("fixed", "free_x", "free_y", "free"))
free <- list(
x = any(scales %in% c("free_x", "free")),
y = any(scales %in% c("free_y", "free"))
)
space <- match.arg(space, c("fixed", "free_x", "free_y", "free"))
space_free <- list(
x = any(space %in% c("free_x", "free")),
y = any(space %in% c("free_y", "free"))
)
if (!is.null(switch) && !switch %in% c("both", "x", "y")) {
stop("switch must be either 'both', 'x', or 'y'", call. = FALSE)
}
# Facets can either be a formula, a string, or a list of things to be
# convert to quoted
if (is.character(facets)) {
facets <- stats::as.formula(facets)
}
if (is.formula(facets)) {
lhs <- function(x) if (length(x) == 2) NULL else x[-3]
rhs <- function(x) if (length(x) == 2) x else x[-2]
rows <- as.quoted(lhs(facets))
rows <- rows[!sapply(rows, identical, as.name("."))]
cols <- as.quoted(rhs(facets))
cols <- cols[!sapply(cols, identical, as.name("."))]
}
if (is.list(facets)) {
rows <- as.quoted(facets[[1]])
cols <- as.quoted(facets[[2]])
}
if (length(rows) + length(cols) == 0) {
stop("Must specify at least one variable to facet by", call. = FALSE)
}
# Check for deprecated labellers
labeller <- check_labeller(labeller)
ggproto(NULL, FacetGrid,
shrink = shrink,
params = list(rows = rows, cols = cols, margins = margins,
free = free, space_free = space_free, labeller = labeller,
as.table = as.table, switch = switch, drop = drop)
)
}
#' @rdname ggplot2-ggproto
#' @format NULL
#' @usage NULL
#' @export
FacetGrid <- ggproto("FacetGrid", Facet,
shrink = TRUE,
compute_layout = function(data, params) {
rows <- as.quoted(params$rows)
cols <- as.quoted(params$cols)
base_rows <- combine_vars(data, params$plot_env, rows, drop = params$drop)
if (!params$as.table) {
rev_order <- function(x) factor(x, levels = rev(ulevels(x)))
base_rows[] <- lapply(base_rows, rev_order)
}
base_cols <- combine_vars(data, params$plot_env, cols, drop = params$drop)
base <- df.grid(base_rows, base_cols)
# Add margins
base <- reshape2::add_margins(base, list(names(rows), names(cols)), params$margins)
# Work around bug in reshape2
base <- unique(base)
# Create panel info dataset
panel <- plyr::id(base, drop = TRUE)
panel <- factor(panel, levels = seq_len(attr(panel, "n")))
rows <- if (is.null(names(rows))) 1L else plyr::id(base[names(rows)], drop = TRUE)
cols <- if (is.null(names(cols))) 1L else plyr::id(base[names(cols)], drop = TRUE)
panels <- data.frame(PANEL = panel, ROW = rows, COL = cols, base,
check.names = FALSE, stringsAsFactors = FALSE)
panels <- panels[order(panels$PANEL), , drop = FALSE]
rownames(panels) <- NULL
panels$SCALE_X <- if (params$free$x) panels$COL else 1L
panels$SCALE_Y <- if (params$free$y) panels$ROW else 1L
panels
},
map_data = function(data, layout, params) {
if (empty(data)) {
return(cbind(data, PANEL = integer(0)))
}
rows <- as.quoted(params$rows)
cols <- as.quoted(params$cols)
vars <- c(names(rows), names(cols))
# Compute facetting values and add margins
margin_vars <- list(intersect(names(rows), names(data)),
intersect(names(cols), names(data)))
data <- reshape2::add_margins(data, margin_vars, params$margins)
facet_vals <- eval_facet_vars(c(rows, cols), data, params$plot_env)
# If any facetting variables are missing, add them in by
# duplicating the data
missing_facets <- setdiff(vars, names(facet_vals))
if (length(missing_facets) > 0) {
to_add <- unique(layout[missing_facets])
data_rep <- rep.int(1:nrow(data), nrow(to_add))
facet_rep <- rep(1:nrow(to_add), each = nrow(data))
data <- plyr::unrowname(data[data_rep, , drop = FALSE])
facet_vals <- plyr::unrowname(cbind(
facet_vals[data_rep, , drop = FALSE],
to_add[facet_rep, , drop = FALSE]))
}
# Add PANEL variable
if (nrow(facet_vals) == 0) {
# Special case of no facetting
data$PANEL <- NO_PANEL
} else {
facet_vals[] <- lapply(facet_vals[], as.factor)
facet_vals[] <- lapply(facet_vals[], addNA, ifany = TRUE)
keys <- plyr::join.keys(facet_vals, layout, by = vars)
data$PANEL <- layout$PANEL[match(keys$x, keys$y)]
}
data[order(data$PANEL), , drop = FALSE]
},
draw_panels = function(panels, layout, x_scales, y_scales, ranges, coord, data, theme, params) {
cols <- which(layout$ROW == 1)
rows <- which(layout$COL == 1)
axes <- render_axes(ranges[cols], ranges[rows], coord, theme, transpose = TRUE)
col_vars <- unique(layout[names(params$cols)])
row_vars <- unique(layout[names(params$rows)])
# Adding labels metadata, useful for labellers
attr(col_vars, "type") <- "cols"
attr(col_vars, "facet") <- "grid"
attr(row_vars, "type") <- "rows"
attr(row_vars, "facet") <- "grid"
strips <- render_strips(col_vars, row_vars, params$labeller, theme)
aspect_ratio <- theme$aspect.ratio
if (is.null(aspect_ratio) && !params$free$x && !params$free$y) {
aspect_ratio <- coord$aspect(ranges[[1]])
}
if (is.null(aspect_ratio)) {
aspect_ratio <- 1
respect <- FALSE
} else {
respect <- TRUE
}
ncol <- max(layout$COL)
nrow <- max(layout$ROW)
panel_table <- matrix(panels, nrow = nrow, ncol = ncol, byrow = TRUE)
# @kohske
# Now size of each panel is calculated using PANEL$ranges, which is given by
# coord_train called by train_range.
# So here, "scale" need not to be referred.
#
# In general, panel has all information for building facet.
if (params$space_free$x) {
ps <- layout$PANEL[layout$ROW == 1]
widths <- vapply(ps, function(i) diff(ranges[[i]]$x.range), numeric(1))
panel_widths <- unit(widths, "null")
} else {
panel_widths <- rep(unit(1, "null"), ncol)
}
if (params$space_free$y) {
ps <- layout$PANEL[layout$COL == 1]
heights <- vapply(ps, function(i) diff(ranges[[i]]$y.range), numeric(1))
panel_heights <- unit(heights, "null")
} else {
panel_heights <- rep(unit(1 * aspect_ratio, "null"), nrow)
}
panel_table <- gtable_matrix("layout", panel_table,
panel_widths, panel_heights, respect = respect, clip = "on", z = matrix(1, ncol = ncol, nrow = nrow))
panel_table$layout$name <- paste0('panel-', rep(seq_len(ncol), nrow), '-', rep(seq_len(nrow), each = ncol))
panel_table <- gtable_add_col_space(panel_table,
theme$panel.spacing.x %||% theme$panel.spacing)
panel_table <- gtable_add_row_space(panel_table,
theme$panel.spacing.y %||% theme$panel.spacing)
# Add axes
panel_table <- gtable_add_rows(panel_table, max_height(axes$x$top), 0)
panel_table <- gtable_add_rows(panel_table, max_height(axes$x$bottom), -1)
panel_table <- gtable_add_cols(panel_table, max_width(axes$y$left), 0)
panel_table <- gtable_add_cols(panel_table, max_width(axes$y$right), -1)
panel_pos_col <- panel_cols(panel_table)
panel_pos_rows <- panel_rows(panel_table)
panel_table <- gtable_add_grob(panel_table, axes$x$top, 1, panel_pos_col$l, clip = "off", name = paste0("axis-t-", seq_along(axes$x$top)), z = 3)
panel_table <- gtable_add_grob(panel_table, axes$x$bottom, -1, panel_pos_col$l, clip = "off", name = paste0("axis-b-", seq_along(axes$x$bottom)), z = 3)
panel_table <- gtable_add_grob(panel_table, axes$y$left, panel_pos_rows$t, 1, clip = "off", name = paste0("axis-l-", seq_along(axes$y$left)), z = 3)
panel_table <- gtable_add_grob(panel_table, axes$y$right, panel_pos_rows$t, -1, clip = "off", name = paste0("axis-r-", seq_along(axes$y$right)), z= 3)
# Add strips
switch_x <- !is.null(params$switch) && params$switch %in% c("both", "x")
switch_y <- !is.null(params$switch) && params$switch %in% c("both", "y")
inside_x <- (theme$strip.placement.x %||% theme$strip.placement %||% "inside") == "inside"
inside_y <- (theme$strip.placement.y %||% theme$strip.placement %||% "inside") == "inside"
strip_padding <- convertUnit(theme$strip.switch.pad.grid, "cm")
panel_pos_col <- panel_cols(panel_table)
if (switch_x) {
if (!is.null(strips$x$bottom)) {
if (inside_x) {
panel_table <- gtable_add_rows(panel_table, max_height(strips$x$bottom), -2)
panel_table <- gtable_add_grob(panel_table, strips$x$bottom, -2, panel_pos_col$l, clip = "on", name = paste0("strip-b-", seq_along(strips$x$bottom)), z = 2)
} else {
panel_table <- gtable_add_rows(panel_table, strip_padding, -1)
panel_table <- gtable_add_rows(panel_table, max_height(strips$x$bottom), -1)
panel_table <- gtable_add_grob(panel_table, strips$x$bottom, -1, panel_pos_col$l, clip = "on", name = paste0("strip-b-", seq_along(strips$x$bottom)), z = 2)
}
}
} else {
if (!is.null(strips$x$top)) {
if (inside_x) {
panel_table <- gtable_add_rows(panel_table, max_height(strips$x$top), 1)
panel_table <- gtable_add_grob(panel_table, strips$x$top, 2, panel_pos_col$l, clip = "on", name = paste0("strip-t-", seq_along(strips$x$top)), z = 2)
} else {
panel_table <- gtable_add_rows(panel_table, strip_padding, 0)
panel_table <- gtable_add_rows(panel_table, max_height(strips$x$top), 0)
panel_table <- gtable_add_grob(panel_table, strips$x$top, 1, panel_pos_col$l, clip = "on", name = paste0("strip-t-", seq_along(strips$x$top)), z = 2)
}
}
}
panel_pos_rows <- panel_rows(panel_table)
if (switch_y) {
if (!is.null(strips$y$left)) {
if (inside_y) {
panel_table <- gtable_add_cols(panel_table, max_width(strips$y$left), 1)
panel_table <- gtable_add_grob(panel_table, strips$y$left, panel_pos_rows$t, 2, clip = "on", name = paste0("strip-l-", seq_along(strips$y$left)), z = 2)
} else {
panel_table <- gtable_add_cols(panel_table, strip_padding, 0)
panel_table <- gtable_add_cols(panel_table, max_width(strips$y$left), 0)
panel_table <- gtable_add_grob(panel_table, strips$y$left, panel_pos_rows$t, 1, clip = "on", name = paste0("strip-l-", seq_along(strips$y$left)), z = 2)
}
}
} else {
if (!is.null(strips$y$right)) {
if (inside_y) {
panel_table <- gtable_add_cols(panel_table, max_width(strips$y$right), -2)
panel_table <- gtable_add_grob(panel_table, strips$y$right, panel_pos_rows$t, -2, clip = "on", name = paste0("strip-r-", seq_along(strips$y$right)), z = 2)
} else {
panel_table <- gtable_add_cols(panel_table, strip_padding, -1)
panel_table <- gtable_add_cols(panel_table, max_width(strips$y$right), -1)
panel_table <- gtable_add_grob(panel_table, strips$y$right, panel_pos_rows$t, -1, clip = "on", name = paste0("strip-r-", seq_along(strips$y$right)), z = 2)
}
}
}
panel_table
},
vars = function(self) {
vapply(c(self$params$rows, self$params$cols), as.character, character(1))
}
)
# Helpers -----------------------------------------------------------------
ulevels <- function(x) {
if (is.factor(x)) {
x <- addNA(x, TRUE)
factor(levels(x), levels(x), exclude = NULL)
} else {
sort(unique(x))
}
}