如何将多个线性回归方程添加到ggplot的底部？

library(ggplot2)

p <- ggplot(data = df, aes(x = x, y = y)) + geom_point()

p <- p + geom_smooth(method = "lm", se = FALSE)

stat_poly_eq <- function(formula, coef.digits = 2, rr.digits = 2, ...) {
  lm_eq <- function(formula) {
    fit <- lm(formula)
    eq <- substitute(italic(y) == a + b %.% italic(x)*","~~italic(r)^2~"="~r2, 
                     list(a = format(fit$coef[[1]], digits = coef.digits), 
                          b = format(fit$coef[[2]], digits = coef.digits), 
                          r2 = format(summary(fit)$r.squared, digits = rr.digits)))
    as.character(as.expression(eq))
  }
  geom <- ggplot2:::ggplot2::GeomFunction$new(
    fun = function(x, y, ...) {
      label <- paste(lm_eq(y ~ x), sep = ", ")
      data.frame(x = mean(x), y = min(y), label = label)
    }, ...)
  ggplot2:::ggplot_add(geom)
}

p <- p + stat_poly_eq(formula = y ~ x)

library(ggplot2)

# 创建一个示例数据框
df <- data.frame(x = c(1, 2, 3, 4, 5), y = c(2, 4, 6, 8, 10))

# 创建基本的ggplot对象并添加散点图和线性回归线
p <- ggplot(data = df, aes(x = x, y = y)) + geom_point() +
  geom_smooth(method = "lm", se = FALSE)

# 创建自定义函数用于添加回归方程
stat_poly_eq <- function(formula, coef.digits = 2, rr.digits = 2, ...) {
  lm_eq <- function(formula) {
    fit <- lm(formula)
    eq <- substitute(italic(y) == a + b %.% italic(x)*","~~italic(r)^2~"="~r2, 
                     list(a = format(fit$coef[[1]], digits = coef.digits), 
                          b = format(fit$coef[[2]], digits = coef.digits), 
                          r2 = format(summary(fit)$r.squared, digits = rr.digits)))
    as.character(as.expression(eq))
  }
  geom <- ggplot2:::ggplot2::GeomFunction$new(
    fun = function(x, y, ...) {
      label <- paste(lm_eq(y ~ x), sep = ", ")
      data.frame(x = mean(x), y = min(y), label = label)
    }, ...)
  ggplot2:::ggplot_add(geom)
}

# 使用自定义函数添加回归方程
p <- p + stat_poly_eq(formula = y ~ x)

# 添加图形标题和轴标签，并自定义图形样式
p <- p + labs(title = "Scatter plot with linear regression", 
              x = "X", y = "Y") +
  theme(plot.title = element_text(hjust = 0.5),
        axis.title = element_text(size = 12))

# 显示图形
print(p)