组合线和条形几何：如何生成正确的图例？

Question

d2 的图例看起来不错；对于d1，我只想在白色/透明背景上显示水平线。

df = data.frame(
  Date = c("2012-11-30", "2012-12-03", "2012-12-04"),
  d1 = c(9, 5, 11),
  d2 = c(4, 6, 3)
)
ggplot(df, aes(Date)) + 
  geom_bar(aes(y = d2, color = "d2"), stat="identity", fill = "red") +
  geom_line(aes(y = d1, group = 1, color = "d1"))  +
  scale_colour_manual("", values=c("d1" = "blue", "d2" = "red")) 

Answer 1

# Bar graph: Notice the placement of fill argument in aes()  
  geom_bar(aes(y=prop.P*100, fill="Seropositive"), stat = "identity",
           position = "dodge", width = 0.5)+

# This line defines the legend for the bar
  scale_fill_manual(name="", values = c("Seropositive"="steelblue3"))+

# Adding errorbar
  geom_errorbar(aes(ymin = ciLow*100, ymax = ciHigh*100), width = 0.2,
                position = position_dodge(width=0.8))+

# Adding the line to the graph. Used the color argument within aes() to define custom colour
  geom_line(aes(y=mmr1_cov*100, group=1, color="MMR1 Coverage"), size=1)+

# Adding points represent the plotted data
  geom_point(aes(x=age, y=mmr1_cov*100), color="red", size=2)+

# Here adding the legend for the line graph and define the colour
  scale_color_manual(name="", values=c("MMR1 Coverage"="red"))+

# Label the axis
  labs(x="Age (Months)", y="Percentage")+

# Place the legend bottom of the graph
  theme(legend.position = "bottom")

Section of the graph displaying the results

Answer 2

这不是一个优雅的解决方案，但至少它给出了一些结果。

我在geom_bar() 中添加了aes(fill="d2") 并删除了fill="red"。然后我为线和条添加了单独的比例。然后在theme() 我从图例条目中删除了灰色背景。

为了确保图例中的 d1 显示在 scale_colour_manual(" ") 中的 d2 之前，引号之间应该有额外的空格（“更长的”名称）。

为了将图例键保留在一行中，legend.box="horizontal" 添加到 theme()

  ggplot(df, aes(Date)) + 
    geom_bar(aes(y = d2,fill="d2"), stat="identity") +
    geom_line(aes(y = d1, group = 1, color = "d1")) +
    scale_colour_manual(" ", values=c("d1" = "blue", "d2" = "red"))+
    scale_fill_manual("",values="red")+
    theme(legend.key=element_blank(),
          legend.title=element_blank(),
          legend.box="horizontal")