#' @include facet-.R
NULL
#' Lay out panels in a grid
#'
#' `facet_grid()` forms a matrix of panels defined by row and column
#' faceting variables. It is most useful when you have two discrete
#' variables, and all combinations of the variables exist in the data.
#' If you have only one variable with many levels, try [facet_wrap()].
#'
#' @param rows,cols A set of variables or expressions quoted by
#' [vars()] and defining faceting groups on the rows or columns
#' dimension. The variables can be named (the names are passed to
#' `labeller`).
#'
#' For compatibility with the classic interface, `rows` can also be
#' 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).
#' @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 `vars(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()]. You can use different labeling
#' functions for different kind of labels, for example use [label_parsed()] for
#' formatting facet labels. [label_value()] is used by default,
#' check it 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.
#' @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 facets `r lifecycle::badge("deprecated")` Please use `rows`
#' and `cols` instead.
#' @param axes Determines which axes will be drawn. When `"margins"`
#' (default), axes will be drawn at the exterior margins. `"all_x"` and
#' `"all_y"` will draw the respective axes at the interior panels too, whereas
#' `"all"` will draw all axes at all panels.
#' @param axis.labels Determines whether to draw labels for interior axes when
#' the `axes` argument is not `"margins"`. When `"all"` (default), all
#' interior axes get labels. When `"margins"`, only the exterior axes get
#' labels and the interior axes get none. When `"all_x"` or `"all_y"`, only
#' draws the labels at the interior axes in the x- or y-direction
#' respectively.
#' @export
#' @seealso
#' The `r link_book("facet grid section", "facet#facet-grid")`
#' @examples
#' p <- ggplot(mpg, aes(displ, cty)) + geom_point()
#'
#' # Use vars() to supply variables from the dataset:
#' p + facet_grid(rows = vars(drv))
#' p + facet_grid(cols = vars(cyl))
#' p + facet_grid(vars(drv), vars(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
#' # faceting variables, the data will be repeated across the missing
#' # combinations:
#' df <- data.frame(displ = mean(mpg$displ), cty = mean(mpg$cty))
#' p +
#' facet_grid(cols = vars(cyl)) +
#' geom_point(data = df, colour = "red", size = 2)
#'
#' # When scales are constant, duplicated axes can be shown with
#' # or without labels
#' ggplot(mpg, aes(cty, hwy)) +
#' geom_point() +
#' facet_grid(year ~ drv, axes = "all", axis.labels = "all_x")
#'
#' # 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(vars(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))
#'
#' # Margins ----------------------------------------------------------
#' \donttest{
#' # Margins can be specified logically (all yes or all no) or for specific
#' # variables as (character) variable names
#' mg <- ggplot(mtcars, aes(x = mpg, y = wt)) + geom_point()
#' 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")
#' }
facet_grid <- function(rows = NULL, cols = NULL, scales = "fixed",
space = "fixed", shrink = TRUE,
labeller = "label_value", as.table = TRUE,
switch = NULL, drop = TRUE, margins = FALSE,
axes = "margins", axis.labels = "all",
facets = deprecated()) {
# `facets` is deprecated and renamed to `rows`
if (lifecycle::is_present(facets)) {
deprecate_warn0("2.2.0", "facet_grid(facets)", "facet_grid(rows)")
rows <- facets
}
# Should become a warning in a future release
if (is.logical(cols)) {
margins <- cols
cols <- NULL
}
scales <- arg_match0(scales %||% "fixed", 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 <- arg_match0(space %||% "fixed", 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"))
)
draw_axes <- arg_match0(axes, c("margins", "all_x", "all_y", "all"))
draw_axes <- list(
x = any(draw_axes %in% c("all_x", "all")),
y = any(draw_axes %in% c("all_y", "all"))
)
# Omitting labels is special-cased internally, so even when no internal axes
# are to be drawn, register as labelled.
axis_labels <- arg_match0(axis.labels, c("margins", "all_x", "all_y", "all"))
axis_labels <- list(
x = !draw_axes$x || any(axis_labels %in% c("all_x", "all")),
y = !draw_axes$y || any(axis_labels %in% c("all_y", "all"))
)
if (!is.null(switch)) {
arg_match0(switch, c("both", "x", "y"))
}
facets_list <- grid_as_facets_list(rows, cols)
# Check for deprecated labellers
labeller <- check_labeller(labeller)
ggproto(NULL, FacetGrid,
shrink = shrink,
params = list(rows = facets_list$rows, cols = facets_list$cols, margins = margins,
free = free, space_free = space_free, labeller = labeller,
as.table = as.table, switch = switch, drop = drop,
draw_axes = draw_axes, axis_labels = axis_labels)
)
}
# Returns a list of quosures objects. The list has exactly two elements, `rows` and `cols`.
grid_as_facets_list <- function(rows, cols) {
is_rows_vars <- is.null(rows) || is_quosures(rows)
if (!is_rows_vars) {
if (!is.null(cols)) {
msg <- "{.arg rows} must be {.code NULL} or a {.fn vars} list if {.arg cols} is a {.fn vars} list."
# Native pipe have higher precedence than + so any type of gg object can be
# expected here, not just ggplot
if (inherits(rows, "gg")) {
msg <- c(
msg,
"i" = "Did you use {.code %>%} or {.code |>} instead of {.code +}?"
)
}
cli::cli_abort(msg)
}
# For backward-compatibility
facets_list <- as_facets_list(rows)
if (length(facets_list) > 2L) {
cli::cli_abort("A grid facet specification can't have more than two dimensions.")
}
# Fill with empty quosures
facets <- list(rows = quos(), cols = quos())
facets[seq_along(facets_list)] <- facets_list
# Do not compact the legacy specs
return(facets)
}
check_object(cols, is_quosures, "a {.fn vars} specification", allow_null = TRUE)
list(
rows = compact_facets(as_facets_list(rows)),
cols = compact_facets(as_facets_list(cols))
)
}
#' @rdname ggplot2-ggproto
#' @format NULL
#' @usage NULL
#' @export
FacetGrid <- ggproto("FacetGrid", Facet,
shrink = TRUE,
compute_layout = function(self, data, params) {
rows <- params$rows
cols <- params$cols
check_facet_vars(names(rows), names(cols), name = snake_class(self))
dups <- intersect(names(rows), names(cols))
if (length(dups) > 0) {
cli::cli_abort(c(
"Faceting variables can only appear in {.arg rows} or {.arg cols}, not both.",
"i" = "Duplicated variables: {.val {dups}}"
), call = call2(snake_class(self)))
}
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$drop)
base <- df.grid(base_rows, base_cols)
if (nrow(base) == 0) {
return(data_frame0(
PANEL = factor(1L),
ROW = 1L,
COL = 1L,
SCALE_X = 1L,
SCALE_Y = 1L
))
}
# Add margins
base <- reshape_add_margins(base, list(names(rows), names(cols)), params$margins)
base <- unique0(base)
# Create panel info dataset
panel <- id(base, drop = TRUE)
panel <- factor(panel, levels = seq_len(attr(panel, "n")))
rows <- if (!length(names(rows))) rep(1L, length(panel)) else id(base[names(rows)], drop = TRUE)
cols <- if (!length(names(cols))) rep(1L, length(panel)) else id(base[names(cols)], drop = TRUE)
panels <- data_frame0(PANEL = panel, ROW = rows, COL = cols, base)
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$ROW else 1L
panels
},
map_data = function(data, layout, params) {
if (empty(data)) {
return(vec_cbind(data %|W|% NULL, PANEL = integer(0)))
}
rows <- params$rows
cols <- params$cols
vars <- c(names(rows), names(cols))
if (length(vars) == 0) {
data$PANEL <- layout$PANEL
return(data)
}
# Compute faceting values and add margins
margin_vars <- list(intersect(names(rows), names(data)),
intersect(names(cols), names(data)))
data <- reshape_add_margins(data, margin_vars, params$margins)
facet_vals <- eval_facets(c(rows, cols), data, params$.possible_columns)
# If any faceting variables are missing, add them in by
# duplicating the data
missing_facets <- setdiff(vars, names(facet_vals))
if (length(missing_facets) > 0) {
to_add <- unique0(layout[missing_facets])
data_rep <- rep.int(1:nrow(data), nrow(to_add))
facet_rep <- rep(1:nrow(to_add), each = nrow(data))
data <- unrowname(data[data_rep, , drop = FALSE])
facet_vals <- unrowname(vec_cbind(
unrowname(facet_vals[data_rep, , drop = FALSE]),
unrowname(to_add[facet_rep, , drop = FALSE]))
)
}
# Add PANEL variable
if (nrow(facet_vals) == 0) {
# Special case of no faceting
data$PANEL <- NO_PANEL
} else {
facet_vals[] <- lapply(facet_vals[], as_unordered_factor)
facet_vals[] <- lapply(facet_vals[], addNA, ifany = TRUE)
layout[] <- lapply(layout[], as_unordered_factor)
keys <- join_keys(facet_vals, layout, by = vars)
data$PANEL <- layout$PANEL[match(keys$x, keys$y)]
}
data
},
attach_axes = function(table, layout, ranges, coord, theme, params) {
# Setup parameters
draw_axes <- params$draw_axes %||% list(x = FALSE, y = FALSE)
axis_labels <- params$axis_labels %||% list(x = TRUE, y = TRUE)
dim <- c(max(layout$ROW), max(layout$COL))
if (!axis_labels$x) {
cols <- seq_len(nrow(layout))
x_order <- as.integer(layout$PANEL[order(layout$ROW, layout$COL)])
} else {
cols <- which(layout$ROW == 1)
x_order <- layout$COL
}
if (!axis_labels$y) {
rows <- seq_len(nrow(layout))
y_order <- as.integer(layout$PANEL[order(layout$ROW, layout$COL)])
} else {
rows <- which(layout$COL == 1)
y_order <- layout$ROW
}
# Render individual axes
ranges <- censor_labels(ranges, layout, axis_labels)
axes <- render_axes(ranges[cols], ranges[rows], coord, theme, transpose = TRUE)
mtx <- function(x, o) matrix(x[o], dim[1], dim[2], byrow = TRUE)
if (draw_axes$x) {
table <- weave_axes(table, lapply(axes$x, mtx, o = x_order))
} else {
table <- seam_table(table, axes$x$top, side = "top", name = "axis-t", z = 3)
table <- seam_table(table, axes$x$bottom, side = "bottom", name = "axis-b", z = 3)
}
if (draw_axes$y) {
table <- weave_axes(table, lapply(axes$y, mtx, o = y_order))
} else {
table <- seam_table(table, axes$y$left, side = "left", name = "axis-l", z = 3)
table <- seam_table(table, axes$y$right, side = "right", name = "axis-r", z = 3)
}
table
},
attach_strips = function(table, layout, params, theme) {
col_vars <- unique0(layout[names(params$cols)])
row_vars <- unique0(layout[names(params$rows)])
attr(col_vars, "type") <- "cols"
attr(row_vars, "type") <- "rows"
attr(col_vars, "facet") <- "grid"
attr(row_vars, "facet") <- "grid"
strips <- render_strips(col_vars, row_vars, params$labeller, theme)
padding <- convertUnit(calc_element("strip.switch.pad.grid", theme), "cm")
switch_x <- !is.null(params$switch) && params$switch %in% c("both", "x")
inside_x <- (calc_element("strip.placement.x", theme) %||% "inside") == "inside"
shift_x <- if (inside_x) 1 else 2
if (switch_x) {
space <- if (!inside_x & table_has_grob(table, "axis-b")) padding
table <- seam_table(
table, strips$x$bottom, side = "bottom", name = "strip-b",
shift = shift_x, z = 2, clip = "on", spacing = space
)
} else {
space <- if (!inside_x & table_has_grob(table, "axis-t")) padding
table <- seam_table(
table, strips$x$top, side = "top", name = "strip-t",
shift = shift_x, z = 2, clip = "on", spacing = space
)
}
switch_y <- !is.null(params$switch) && params$switch %in% c("both", "y")
inside_y <- (calc_element("strip.placement.y", theme) %||% "inside") == "inside"
shift_y <- if (inside_y) 1 else 2
if (switch_y) {
space <- if (!inside_y & table_has_grob(table, "axis-l")) padding
table <- seam_table(
table, strips$y$left, side = "left", name = "strip-l",
shift = shift_y, z = 2, clip = "on", spacing = space
)
} else {
space <- if (!inside_y & table_has_grob(table, "axis-r")) padding
table <- seam_table(
table, strips$y$right, side = "right", name = "strip-r",
shift = shift_y, z = 2, clip = "on", spacing = space
)
}
table
},
vars = function(self) {
names(c(self$params$rows, self$params$cols))
}
)
# Helpers -----------------------------------------------------------------
ulevels <- function(x, na.last = TRUE) {
if (is.factor(x)) {
x <- addNA(x, TRUE)
factor(levels(x), levels(x), exclude = NULL)
} else {
sort(unique0(x), na.last = na.last)
}
}
table_has_grob <- function(table, pattern) {
grobs <- table$grobs[grep(pattern, table$layout$name)]
!all(vapply(grobs, is.zero, logical(1)))
}
seam_table <- function(table, grobs = NULL, side, shift = 1, name, z = 1,
clip = "off", spacing = NULL) {
if (is.null(grobs)) {
return(table)
}
panel_col <- panel_cols(table)
panel_row <- panel_rows(table)
row <- switch(
side,
bottom = max(panel_row$b) + shift - 1L,
top = min(panel_row$t) - shift,
panel_row$t
)
col <- switch(
side,
right = max(panel_col$r) + shift - 1L,
left = min(panel_col$l) - shift,
panel_col$l
)
if (!is.null(spacing)) {
table <- switch(
side,
bottom = , top = gtable_add_rows(table, spacing, row),
left = , right = gtable_add_cols(table, spacing, col)
)
row <- row + as.numeric(side == "bottom")
col <- col + as.numeric(side == "right")
}
table <- switch(
side,
bottom = , top = gtable_add_rows(table, max_height(grobs), row),
left = , right = gtable_add_cols(table, max_width(grobs), col)
)
name <- paste(name, seq_along(grobs), sep = "-")
row <- row + as.numeric(side %in% c("top", "bottom"))
col <- col + as.numeric(side %in% c("left", "right"))
gtable_add_grob(table, grobs, t = row, l = col, name = name, z = z, clip = clip)
}
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