ggplot2重新排序X轴后geom_smooth不显示的问题求助

reorder(n, ni)会将原本数值型的n转换为因子类型，而geom_smooth中使用的poly(x,4)要求自变量是连续数值型变量，因子无法被多项式拟合，因此拟合线无法生成。

提供两种可行的解决思路：

方案1：提前生成排序后的连续型x变量（推荐） #

先在数据集中生成一个按ni排序的连续型位置变量，用它作为拟合的x轴，同时替换刻度标签为原n值，兼顾排序和拟合需求：

# 加载dplyr用于数据处理（未安装先运行install.packages("dplyr")）
library(dplyr)

# 按Type分组，每组内按ni排序，生成连续的排序位置变量
GGCV <- GGCV %>%
  group_by(Type) %>%
  arrange(ni) %>%
  mutate(x_sorted = row_number()) %>%
  ungroup()

# 绘图代码
p11 <- ggplot(GGCV, 
              aes(x = x_sorted, 
                  y = Value, 
                  color = Type)) +
  geom_point(alpha = 0.7, size = 3) +
  geom_smooth(se = FALSE, 
              method = "lm", 
              formula = y ~ poly(x, 4), 
              size = 1) +
  labs(x = "Areas, sorted by sample size",
       title = "Coefficient of Variation %",
       y = "CV%",
       color = "Estimator") +
  scale_color_manual(values = c("#999999", "#E69F00", "#00A550")) +
  # 将x轴刻度替换为原n值，保持排序后的顺序
  scale_x_continuous(breaks = 1:35, 
                     labels = GGCV %>% distinct(x_sorted, n) %>% arrange(x_sorted) %>% pull(n)) +
  coord_cartesian(ylim = c(0, 35)) +
  theme(legend.position = "none") +
  scale_y_continuous(labels = scaleFUN)

方案2：在geom_smooth中单独指定连续型x变量 #

保持散点图的x轴为reorder(n, ni)的因子排序，同时在geom_smooth中手动指定x为连续型的ni（因为reorder(n, ni)的顺序完全对应ni的排序）：

p11 <- ggplot(GGCV, 
              aes(x = reorder(n, ni), 
                  y = Value, 
                  color = Type)) +
  geom_point(alpha = 0.7, size = 3) +
  # 单独指定x为连续型的ni，继承color分组进行拟合
  geom_smooth(aes(x = ni), 
              se = FALSE, 
              method = "lm", 
              formula = y ~ poly(x, 4), 
              size = 1) +
  labs(x = "Areas, sorted by sample size",
       title = "Coefficient of Variation %",
       y = "CV%",
       color = "Estimator") +
  scale_color_manual(values = c("#999999", "#E69F00", "#00A550")) +
  coord_cartesian(ylim = c(0, 35)) +
  theme(legend.position = "none") +
  scale_y_continuous(labels = scaleFUN)

内容的提问来源于stack exchange，提问作者Lorenzo