仅在 R 中 ggplot 的第一个方面进行注释？

Question

我有以下代码生成一个 ggplot，它在两个 facets 上都有 text（即“校准”）。我希望 text 仅出现在第一个 facet 上。我尝试了几件事但没有成功。任何帮助将不胜感激。

library(ggplot2)
library(lubridate)

set.seed(123)

DF1 <- data.frame(Date = seq(as.Date("2001-01-01"), to = as.Date("2005-12-31"), by = "1 month"),
                  Ob = runif(60,1,5), L95 =runif(60, 0,4), U95 = runif(60,2,7), Sim = runif(60,1,5),
                  Loc = rep("Upstream", 60))

DF2 <- data.frame(Date = seq(as.Date("2001-01-01"), to = as.Date("2005-12-31"), by = "1 month"),
                  Ob = runif(60,1,5), L95 =runif(60, 0,4), U95 = runif(60,2,7), Sim = runif(60,1,5),
                  Loc = rep("Downstream", 60))

DF <- dplyr::bind_rows(DF1,DF2)

DF$Loc <- factor(DF$Loc, levels = c("Upstream","Downstream"))


ggplot(DF, aes(x = Date))+
  geom_ribbon(aes(ymin = L95, ymax = U95), fill = "grey30", alpha = 0.4)+
  geom_line(aes(y = Ob, color = "blue"), size = 1 )+
  geom_line(aes(y = Sim, color = "black"), size =  1, linetype = "dashed")+
  geom_vline(xintercept = as.Date("2004-12-01"),color = "red", size = 1.30)+
  facet_wrap(~ Loc, ncol = 1, scales = "free_y")+ 
  theme_bw()+
  annotate(geom = "text", x = as.Date("2002-01-01"), y = 4, label = "Calibration")

Answer 1

试试这个技巧：

library(ggplot2)
#Code
ggplot(DF, aes(x = Date))+
  geom_ribbon(aes(ymin = L95, ymax = U95), fill = "grey30", alpha = 0.4)+
  geom_line(aes(y = Ob, color = "blue"), size = 1 )+
  geom_line(aes(y = Sim, color = "black"), size =  1, linetype = "dashed")+
  geom_vline(xintercept = as.Date("2004-12-01"),color = "red", size = 1.30)+
  facet_wrap(~ Loc, ncol = 1, scales = "free_y")+ 
  theme_bw()+
  geom_text(data=data.frame(Date=as.Date("2002-01-01"),y=4,
                            label = "Calibration",Loc='Upstream'),
            aes(y=y,label=label))

输出：

你也可以在geom_text()这边使用Loc=unique(DF$Loc)[1]。它将产生相同的输出。

仅在 R 中 ggplot 的第一个方面进行注释？

Annotation on only the first facet of ggplot in R?

text

annotations

r

ggplot2

facet-wrap