如何仅更改图例中的geom绘图顺序？

Question

我在ggplot2中制作了一个包含geom_pointrange和geom_line的情节。我看到当我改变geoms的顺序时，要么将点绘制在行的顶部，要么反之亦然。图例还会根据相同的几何排序更改哪个geom在另一个上面绘制。但是，我希望首先绘制线，然后绘制顶部的点范围，在图中本身，与图例中的相反。这可能吗？我非常感谢任何意见。

这是我用来制作图的代码。

md.figd2 <- structure(list(date = c("2013-05-28", "2013-07-11", "2013-09-22", 
"2013-05-28", "2013-07-11", "2013-09-22", "2013-05-28", "2013-07-11", 
"2013-09-22"), trt = structure(c(3L, 3L, 3L, 1L, 1L, 1L, 2L, 
2L, 2L), .Label = c("- Fescue", "- Random", "Control"), class = "factor"), 
means = c(1, 0.921865257043089, 0.793438250521971, 1, 0.878305313846414, 
0.85698797555687, 1, 0.840679145697309, 0.798547331410388
), mins = c(1, 0.87709562979756, 0.72278951032918, 1, 0.816185624483356, 
0.763720265496049, 1, 0.780804129401513, 0.717089626439849
), maxes = c(1, 0.966634884288619, 0.864086990714762, 1, 
0.940425003209472, 0.950255685617691, 1, 0.900554161993105, 
0.880005036380927)), .Names = c("date", "trt", "means", "mins", 
"maxes"), row.names = c(NA, 9L), class = "data.frame")

library(ggplot2)
dplot1.ysc <- scale_y_continuous(limits=c(0,1), breaks=seq(0,1,.2), name='Proportion mass lost')
dplot1.xsc <- scale_x_date(limits=as.Date(c('2013-05-23', '2013-10-03')), labels=c('May 28', 'July 11', 'Sep 22'), breaks=md.figdata$date, name='Date')
dplot1.csc <- scale_color_manual(values=c('grey20','grey50','grey80'))
dplot1.lsc <- scale_linetype_manual(values=c('solid','dotted','dashed'))
djitter <- rep(c(0,-1,1), each=3)

# This one produces the plot with the legend I want.
dplot1b <- ggplot(md.figd2, aes(x=date + djitter, y=means, group=trt)) + geom_pointrange(aes(ymin=mins, ymax=maxes, color=trt), size=2) + geom_line(aes(linetype=trt), size=1)
# This one produces the plot with the points on the main plot that I want.
dplot1b <- ggplot(md.figd2, aes(x=date + djitter, y=means, group=trt)) + geom_line(aes(linetype=trt), size=1) + geom_pointrange(aes(ymin=mins, ymax=maxes, color=trt), size=2)

dplot1b + dplot1.xsc + dplot1.ysc + dplot1.csc + dplot1.lsc

Answer 1

您可以使用gtable::gtable_filter从您想要的地图中提取图例，然后gridExtra::grid.arrange重新创建您想要的地图

# the legend I want
plot1a <- ggplot(md.figd2, aes(x=date , y=means, group=trt)) + 
  geom_pointrange(aes(ymin=mins, ymax=maxes, color=trt), size=2, 
                      position = position_dodge(width=1)) + 
  geom_line(aes(linetype=trt), size=1)
# This one produces the plot with the points on the main plot that I want.
dplot1b <- ggplot(md.figd2, aes(x=date, y=means, group=trt)) + 
  geom_line(aes(linetype=trt), size=1) + 
  geom_pointrange(aes(ymin=mins, ymax=maxes, color=trt), size=2)

w <- dplot1b + dplot1.xsc + dplot1.ysc + dplot1.csc + dplot1.lsc
# legend
l <- dplot1a + dplot1.xsc + dplot1.ysc + dplot1.csc + dplot1.lsc

library(gtable)
library(gridExtra)
# extract legend ("guide-box" element)
leg <- gtable_filter(ggplot_gtable(ggplot_build(l)), 'guide-box')
# plot the two components, adjusting the widths as you see fit.
grid.arrange(w + theme(legend.position='none'),leg,ncol=2, widths = c(3,1))

另一种方法是简单地将您想要的图例中的图例替换为您想要提取的图例（使用gtable_filter）

# create ggplotGrob of plot you want
wGrob <- ggplotGrob(w)
# replace the legend
wGrob$grobs[wGrob$layout$name == "guide-box"][[1]] <- leg
grid.draw(wGrob)

Answer 2

快速而肮脏。要在图形和图例中获得正确的绘图顺序，请添加如下图层：（1）geom_pointrange，（2）geom_line，然后（3）第二个geom_pointrange没有图例（show.legend = FALSE）。

ggplot(md.figd2, aes(x = date, y = means, group = trt)) +
  geom_pointrange(aes(ymin = mins, ymax = maxes, color = trt),
                  position = position_dodge(width = 5), size = 2) +
  geom_line(aes(linetype = trt), size = 1) +
  geom_pointrange(aes(ymin = mins, ymax = maxes, color = trt),
                  position = position_dodge(width = 5), size = 2,
                  show.legend = FALSE) +
  scale_y_continuous(limits = c(0,1), breaks = seq(0,1, 0.2), name = 'Proportion mass lost') +
  scale_x_date(limits = as.Date(c('2013-05-23', '2013-10-03')), name = 'Date') +
  scale_color_manual(values = c('grey20', 'grey50', 'grey80')) +
  scale_linetype_manual(values = c('solid', 'dotted', 'dashed'))