ggplot_equation

library(ggpubr)
x <- 1:100
y <- (x + x^2 + x^3) + rnorm(length(x), mean = 0, sd = mean(x^3) / 4)
my.data <- data.frame(x, y, group = c("A", "B"),
                      y2 = y * c(0.5,2), block = c("a", "a", "b", "b"))

# Fit polynomial regression line and add labels
formula <- y ~ poly(x, 3, raw = TRUE)
p <- ggplot(my.data, aes(x, y2, color = group)) +
  geom_point() +
  stat_smooth(aes(fill = group, color = group), method = "lm", formula = formula) +
  stat_regline_equation(
    aes(label =  paste(..eq.label.., ..adj.rr.label.., sep = "~~~~")),
    formula = formula
  ) +
  theme_bw()
ggpar(p, palette = "jco")

# Opcion 2

ggplot(my.data, aes(x, y2)) +
  geom_point() +
  facet_wrap("group")+
  stat_smooth(method = "lm", formula = formula) +
  stat_regline_equation(formula = formula,
    aes(label =  paste(..eq.label.., ..adj.rr.label.., sep = "\n")),
    label.y = Inf, vjust = 2,
  ) +
  theme_bw(base_size = 12) 

ggsave(file="myplot.tiff", device = "tiff", width = 6, height = 4, scale=1.2)