需要在ggplot中添加图例和修复轴

如何解决需要在ggplot中添加图例和修复轴

我是 ggplot 的新手，我正在尝试弄清楚如何向图形添加图例并重新标记 x 轴。我已经附上了绘图代码和 resulting graph 。我想添加一个图例来解释蓝线以及绿点和红点是什么。我还希望 x 轴上的年份显示为 2018,2019,...,2020 而不是 2017.5,2010.0,2020.0。我在在线文档中找不到解决方案。感谢您的帮助。

  ggplot(data = annual_rate_preds) + 
    geom_point(mapping = aes(x = year,y = predicted),color = 'green') +
    geom_line(mapping = aes(x = year,y = observed),color = 'blue') + 
    geom_point(data = backfit_rate_preds,mapping = aes(x = target_year,y = rate_pred),shape = 18,color = 'red',size = 2) +
    theme(plot.title = element_text(size = 10))

解决方法

使用一些随机示例数据可以这样实现：

1. 使用 scale_x_continuous(breaks = scales::pretty_breaks()) 可以提供漂亮的 x 轴中断和标签
2. 要获得图例，您必须映射美学，即在 aes() 内移动 color。然后可以通过 scale_color_manual
设置颜色值
3. 轴、图例、...的标签可以通过 labs()
设置
4. 最棘手的部分是让图例正确。为此，我使用 guides 和 guide_legend 来调整图例，使得 observed 只显示一条实线，而其他类别只显示点（形状 16）。

library(ggplot2)

set.seed(42)
annual_rate_preds <- data.frame(
  predicted = runif(13,-.1,.1),observed = runif(13,year = 2008:2020
)

backfit_rate_preds<- data.frame(
  rate_pred = runif(13,target_year = 2008:2020
)

ggplot(data = annual_rate_preds) + 
  geom_point(mapping = aes(x = year,y = predicted,color = 'predicted')) +
  geom_line(mapping = aes(x = year,y = observed,color = 'observed')) + 
  geom_point(data = backfit_rate_preds,mapping = aes(x = target_year,y = rate_pred,color = 'rate_pred'),shape = 18,size = 2) +
  scale_x_continuous(breaks = scales::pretty_breaks()) +
  scale_color_manual(values = c(predicted = "green",observed = "blue",rate_pred = "red")) +
  theme(plot.title = element_text(size = 10)) +
  guides(color = guide_legend(override.aes = list(linetype = c("solid","blank","blank"),shape = c(NA,16,16)))) +
  labs(x = "Year",y = NULL,color = NULL)