r - 添加 geom_rect 时对象消失

Question

我有数据:

Distance   Average    Standard.error     CI
   -300  0.9338864     0.01409078   0.02761792
   -150  0.9339457     0.02097350   0.04110805
    -50  0.9495119     0.01359277   0.02664183
     50  0.8588988     0.03599673   0.07055359
    150  0.8531203     0.03047781   0.05973651
    300  0.7945437     0.05874081   0.11513199

我正在 ggplot2 中创建一个图表，到目前为止我的代码是:

ggplot(data = Test, aes(x = Distance, y = Average))+
  geom_errorbar(aes(ymin = Average - CI, ymax = Average + CI), width = 5)+
  geom_point(data = Test, aes(x = Distance, y = Average), stat = "identity", 
             point = 21, fill = "white")+
  scale_x_continuous(breaks = seq(-300,300,100))+
  scale_y_continuous(breaks = seq(0.6,1,0.05))+
  theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
        panel.background = element_blank(), axis.line = element_line(colour = "black"),
        axis.text.x = element_text(colour = "black"), 
        axis.text.y = element_text(colour= "black"))

我想在 x 轴上从 -300 到 0 的图表中添加灰色背景，因此我创建了此数据框:

background <- data.frame( xstart = 300, xend = 0, col = "grey")

然后将此行添加到图表的脚本中:

geom_rect(data = background, aes(xmin = xstart, xmax = xend, ymin = -Inf, ymax = Inf,
                                 fill = col), alpha = 0.4)

所以图表的代码现在看起来像这样:

ggplot(data = Test, aes(x = Distance, y = Average))+
  geom_rect(data = background, aes(xmin = xstart, xmax = xend, ymin = -Inf,    ymax = Inf,
                                   fill = col), alpha = 0.4)+
  geom_errorbar(aes(ymin = Average - CI, ymax = Average + CI), width = 5)+
  geom_point(data = Test, aes(x = Distance, y = Average), stat = "identity", 
             point = 21, fill = "white")+
  scale_x_continuous(breaks = seq(-300,300,100))+
  scale_y_continuous(breaks = seq(0.6,1,0.05))+
  theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
        panel.background = element_blank(), axis.line = element_line(colour = "black"),
        axis.text.x = element_text(colour = "black"), 
        axis.text.y = element_text(colour= "black"))

但是现在当我尝试生成图表时收到一条错误消息:

Error in eval(expr, envir, enclos) : object 'Distance' not found

在添加 geom_rect 行之前，图表生成得很好，为什么添加该行会使“距离”消失？

Answer 1

我认为这是因为 geom_rect 从最初的 ggplot 调用中获取了 x 和 y 美学(即使它不需要或理解它们)并且无法在背景中找到它们。

为什么不直接输入xstart、xend等而不是创建背景？

ggplot(data = Test, aes(x = Distance, y = Average))+
  geom_rect(aes(xmin = 0, xmax = 300, ymin = -Inf, ymax = Inf),
                                   fill = 'grey', alpha = 0.4)+
  geom_errorbar(aes(ymin = Average - CI, ymax = Average + CI), width = 5)+
  geom_point(data = Test, aes(x = Distance, y = Average), stat = "identity", 
             point = 21, fill = "white")+
  scale_x_continuous(breaks = seq(-300,300,100))+
  scale_y_continuous(breaks = seq(0.6,1,0.05))+
  theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(),
        panel.background = element_blank(), axis.line = element_line(colour = "black"),
        axis.text.x = element_text(colour = "black"), 
        axis.text.y = element_text(colour= "black"))

注意 - 我从geom_rect中的“aes”中取出了“fill”，以便填充颜色被解释为文字颜色“grey”，而不是发生的一个因素 具有值“灰色”(然后 ggplot 将使用它通常用于因子的任何默认配色方案)。我认为您实际上可以从对 geom_rect 的 aes 调用中获取一切。