问质感geom_ribbon，类似于桶形图，它有参数a)密度和b)角度

EN

remotes::install_github("coolbutuseless/ggpattern")
library(ggpattern)

x <- seq(pi/2, 20, 0.1)
df <- data.frame(x, lower = 10 * (cos(x)/x - .3), upper = (10 * -cos(x)/x + .3))
ggplot(df) +
  geom_ribbon_pattern(aes(x, ymin = lower, ymax = upper), fill = "gray95",
                      color = "black", 
                      pattern = "stripe",
                      pattern_fill = "gray80",
                      pattern_angle = 45,
                      pattern_density = 0.2,
                      pattern_spacing = 0.05) +
  coord_equal() +
  theme_classic()