如果您有兴趣以ggplot2更多和其他方式进行修改，我推荐使用小插图：
vignette("extending-ggplot2")
现在对于您手头的问题，我认为干净解决方案的捷径如下：
library(ggplot2)
DF <- data.frame(labelx = rep(c('my long label','short'), c(2,26)),
labely = rep(c('a','b'), each = 14),
x = c(letters[1:2], letters[1:26]),
y = LETTERS[6:7],
i = rnorm(28))
# ad-hoc replacement for the "draw_panels" method, sorry for the hundred lines of code...
# only modification is marked with a comment
draw_panels_new <- 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)])
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$ROW)
panel_table <- matrix(panels, nrow = nrow, ncol = ncol, byrow = TRUE)
if (params$space_free$x) {
ps <- layout$PANEL[layout$ROW == 1]
widths <- vapply(ps, function(i) diff(ranges[[i]]$x.range), numeric(1))
# replaced "widths" below with custom manual values c(1,4)
panel_widths <- unit(c(1,4), "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$panel.spacing)
panel_table <- gtable_add_rows(panel_table, max_height(axes$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$right)), z = 3)
switch_x <- !is.null(params$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
}
继续新代码块以停止滚动：
# need to pre-set the same environment to find things like e.g.
# gtable_matrix() from package gtable
environment(draw_panels_new) <- environment(FacetGrid$draw_panels)
# assign custom method
FacetGrid$draw_panels <- draw_panels_new
# happy plotting
ggplot(DF, aes(x, y, color = i)) +
geom_point() +
facet_grid(labely~labelx, scales = 'free_x', space = 'free_x')
我说快捷方式是因为您当然可以编写自己的facet_grid_new附加版本，允许您c(1,4)灵活地将上面的值作为 extra传递params。
当然你可以让你自己的ggproto对象继承自FacetGrid...
编辑：
另一种更灵活的简单方法是添加一个 custom option，例如：
options(facet_size_manual = list(width = c(1,4), height = NULL))
然后可以draw_panels像这样在自定义方法中使用它：
if (!is.null(facet_width <- getOption("facet_size_manual")$width))
widths <- facet_width
