R 在彩色面板背景和不同颜色的矩形上覆盖网格

我正在用R中的ggplot2绘制图表。我想用一种颜色给面板背景上色，用另一种颜色给面板内的矩形上色。我希望网格线覆盖面板和矩形

如果我不给面板背景上色，多亏了AF7和zx8754，我有了一个很好的解决方案。但是如果我也尝试给面板背景上色，它就不起作用了

这是一个reprex：

library(ggplot2)
t <- c(1,2,3)
a <- c(5,4,1)
b <- c(3,2,4)
df <- data.frame(t,a,b)

ggplot(df) +
  geom_rect(xmin=2,xmax=3,ymin=-Inf,ymax=Inf,fill="gray") +

  # The code works fine without this next line, but the panel colour is the default (white)
  # I want the background colour to be lightblue except for the rectangle
  theme(panel.background = element_rect(fill = "lightblue")) +

  # Changing NA to "lightblue" in the line below does not work either
  theme(panel.background = element_rect(fill = NA),panel.ontop = TRUE) +

  theme(panel.grid.minor=element_line(colour="hotpink",size=0.5)) +
  theme(panel.grid.major=element_line(colour="green",size=0.5)) +
  geom_line(aes(x=t,y=a),colour="red") +
  geom_line(aes(x=t,y=b),colour="blue")

库（ggplot2）
t在ggplot中，面板背景和网格层包含在同一个grob中。因此，要么两者都位于geom层下方（默认值
panel.ontop=FALSE
），要么都位于geom层上方（
panel.ontop=TRUE
）。这里有两种可能的解决方法供考虑：

使用
panel.ontop=TRUE
，保持面板背景透明，并使用所需颜色为整个绘图背景上色：

保留默认值
panel.ontop=FALSE
，然后将底层网格线移动到顶部：
p谢谢林子江。伟大的解决方案。
ggplot(df) +
  geom_rect(xmin=2,xmax=3,ymin=-Inf,ymax=Inf,fill="gray") +
  geom_line(aes(x=t,y=a),colour="red") +
  geom_line(aes(x=t,y=b),colour="blue")+

  theme(plot.background = element_rect(fill = "lightblue"), # change this line to plot.background
        panel.background = element_rect(fill = NA),
        panel.ontop = TRUE,
        panel.grid.minor=element_line(colour="hotpink",size=0.5),
        panel.grid.major=element_line(colour="green",size=0.5)) 

p <- ggplot(df) +
  geom_rect(xmin=2,xmax=3,ymin=-Inf,ymax=Inf,fill="gray") +
  geom_line(aes(x=t,y=a),colour="red") +
  geom_line(aes(x=t,y=b),colour="blue")+

  theme(panel.background = element_rect(fill = "lightblue"),
        panel.grid.minor=element_line(colour="hotpink",size=0.5),
        panel.grid.major=element_line(colour="green",size=0.5)) 

# convert from ggplot object to grob object
gp <- ggplotGrob(p) 

# make a copy of the grob that contains the panel background (first child) & panel grids (all subsequent children),
# then drop the panel background grob (i.e. only keep the grobs for grids)
panel.grid.grob <- gp$grobs[[6]]$children[[1]]
panel.grid.grob$children[[1]] <- zeroGrob()

# leave only the panel background grob in its original slot
gp$grobs[[6]]$children[[1]] <- gp$grobs[[6]]$children[[1]]$children[[1]]

# add back grid grobs on top of panel
gp <- gtable::gtable_add_grob(gp, panel.grid.grob, t = 7, l = 5)

# plot result
grid::grid.draw(gp)