使用facet_wrap时stat_poly_eq标签手动定位失效问题求助

现有如下结构的数据框df：

# 创建示例数据
RE <- c(0.95, 0.8, 0.7, 0.85, 0.5, 0.3, 1, 0.8, 0.2, 0.95, 0.4, 0)
TimeSinceStart <- c(10, 20, 30, 10, 20, 30, 10, 20, 30, 10, 20, 30)
Name <- c("A","A","A","B","B","B", "A","A","A","B","B","B")
VaporPressure <- c(1.1, 1.1, 1.1, 0.002, 0.002, 0.002, 1.1, 1.1, 1.1, 0.002, 0.002, 0.002)
Aircleaner <- c("P1","P1","P1","P1","P1","P1","P2","P2","P2","P2","P2","P2")
 
# 创建数据框
df <- data.frame(RE = RE, TimeSinceStart = TimeSinceStart, Name = Name, VaporPressure = VaporPressure, Aircleaner = Aircleaner,
                 stringsAsFactors = FALSE)

# 定义公式
my.formula <- y ~ x

其中Name与VaporPressure一一对应。需要绘制线性回归图，分析不同Aircleaner类别下log10(VaporPressure)与RE的相关性，使用stat_poly_eq并通过label.y手动设置公式标签位置时，设置失效——所有分面的标签都仅使用label.y的第一个值。尝试过label_repel，但仍会与数据点重叠（实际数据点数量更多）。

在ggplot的aes()中添加group = Aircleaner即可解决标签位置失效的问题，有效代码如下：

ggplot(data = df, mapping = aes(log10(VaporPressure), RE, group = Aircleaner, color=TimeSinceStart))+
  geom_point()+
  geom_smooth(method = "lm", se=FALSE, formula = my.formula, size=.7, color="black") +
  stat_poly_eq(geom = "label_npc",
               formula = my.formula, parse = TRUE,
               aes(label =  paste(..eq.label.., ..rr.label.., sep = "*plain(\",\")~~")),
               color="black", size = 3,
               label.y = c(0.3, 0.5))+
  facet_wrap(Aircleaner~., ncol = 2)+
  scale_color_continuous(name = "Operating time (h)")+
  labs(x = bquote(log[10](p[v])), y = "RE (%)", title = NULL)+
  theme(legend.position = "top")

内容的提问来源于stack exchange，提问作者Sara Bjerre Sørensen