绘制渐变中的背景色

问题描述

此代码产生下面的第一个图:

This code produces the first plot below:

water.height <- seq(0, 5, 1)
y <- seq(0, 1500, length.out = 6)
df <- data.frame(water.height, y)

library(ggplot2)
ggplot(df, aes(water.height, y)) + geom_blank()+ theme_bw()

我已经在这个蓝色背景中照相了.

I have photoshopped in this blue background:

我可以使用R代码产生相同的蓝色背景吗?

Can I produce the same blue background with R code?

推荐答案

与 ggplot2方法.从那里复制:

library(grid)
g <- rasterGrob(blues9, width=unit(1,"npc"), height = unit(1,"npc"),
interpolate = TRUE)
# grid.draw(g)

library(ggplot2)
ggplot(mtcars, aes(factor(cyl))) + # add gradient background
   annotation_custom(g, xmin=-Inf, xmax=Inf, ymin=-Inf, ymax=Inf) +
   geom_bar() # add data layer

---

我自己的方法:

和往常一样，我无法与 baptiste 的简单优雅解决方案竞争，以解决网格图形问题，但是在这里自从我从事所有工作以来，这就是我的方法:

As usual, I cannot compete with the simple elegance of baptiste's solutions for problems with grid graphics, but here is my approach since I went to all that work:

gg.background.fill <- function(gg.plot, cols = "white", which = "x") {
  #does not work with facets

  stopifnot(which %in% c("x", "y"))
  which1 <- if (which == "x") "width" else "height"

  require(gridExtra)

  g <- ggplotGrob(gg.plot)
  #g <- ggplotGrob(p)
  gg <- g$grobs
  findIt <- vapply(gg, function(x) grepl("GRID.gTree", x$name, fixed = TRUE), TRUE)
  n1 <- getGrob(gg[findIt][[1]], "grill.gTree", grep=TRUE)$name
  n2 <- getGrob(gg[findIt][[1]], "panel.background.rect", grep=TRUE)$name
  gg[findIt][[1]]$children[[n1]]$children[[n2]]$gp$fill <- cols
  x <- gg[findIt][[1]]$children[[n1]]$children[[n2]][[which]]
  w <- gg[findIt][[1]]$children[[n1]]$children[[n2]][[which1]]
  attr <- attributes(x)
  x <- seq(0 + c(w)/length(cols)/2, 1 - c(w)/length(cols)/2, length.out = length(cols))
  attributes(x) <- attr
  gg[findIt][[1]]$children[[n1]]$children[[n2]][[which]] <- x
  w <- c(w)/length(cols)
  attributes(w) <- attr
  gg[findIt][[1]]$children[[n1]]$children[[n2]][[which1]] <- w
  g$grobs <- gg
  class(g) = c("arrange", "ggplot", class(g))
  g
}
p1 <-  gg.background.fill(p, colorRampPalette(c("red", "blue"))(100))
print(p1)

p2 <-  gg.background.fill(p, colorRampPalette(c("red", "blue"))(100), "y")
print(p2)

这修改了可能被认为是优势的现有背景，但是与annotation_custom方法相反，它不适用于分面.为此，需要做更多的工作.

This modifies the existing background which might be considered an advantage, but in contrast to the annotation_custom approach it doesn't work with faceting. More work would be required for that.

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