如何使用 ggplot 中的两个数据集在闪避条形图上叠加折线图？

Question

我正在尝试生成一个闪避条形图，显示每个报告日的报告年龄分布，并将每天的总报告覆盖在关键报告年龄上。

当我将线条添加到条形图时，出现错误：

Error in `geom_line()`:
! Problem while computing aesthetics.
ℹ Error occurred in the 4th layer.
Caused by error:
! object 'ReportAge' not found

这是我的可重现示例：

dt1 <- expand.grid("ReportDate" = seq(ymd("2024-04-25"),
                                      ymd("2024-05-01"),
                                      by = "day"),
                   "ReportAge" = seq(1,7,1)) %>%
  mutate(n = sample(0:10, n(), replace = TRUE)) %>%
  arrange(ReportDate) %>%
  mutate(as.factor(ReportAge))
dt2 <- dt1 %>%
  filter(as.numeric(ReportAge) > 5) %>%
  group_by(ReportDate) %>%
  summarize(OldReports = sum(n))

graph <- dt1 %>% 
  ggplot(aes(x = ReportDate, y = n, fill = ReportAge)) +
  geom_bar(stat = "identity",
           color = "black", 
           position = position_dodge2(width = 0.9, 
                                      preserve = "single")) +
  geom_text(aes(y= -1, label = ReportAge), 
            color = "black", 
            position = position_dodge2(width = 0.9, preserve = "single"),
            size = 3.5) +
  geom_text(aes(label = n),
            color = "red", 
            vjust = -0.3, 
            position = position_dodge2(width = 0.9, preserve = "single")) +
  guides(fill = guide_legend(override.aes = list(size = 0.5))) +
  scale_x_date(date_breaks = "day", date_labels = "%b %d") +
  theme_minimal()

graph2 <- graph +
  geom_line(data = dt2, mapping = aes(x = ReportDate, y = OldReports), color = "red")

在此图中看起来不错，但 graph2 抛出了上述错误。

Answer 1

改变它

graph2 <- graph +
  geom_line(data = dt2, mapping = aes(x = ReportDate, y = OldReports, fill=NULL), color = "red")

geom_line

正在继承您对

aes()

的调用中的

ggplot()

。基本上，您为每个图层设置

fill = ReportAge

，当您添加额外的

geom_line

时，

dt2

数据源没有名为

ReportAge

的列，因此您会收到错误。您可以通过设置为 NULL 来“取消映射”值