[R] 두개의 세로축 그리기 (dual y-axis)

> ggplot(data, aes(x = a) +

   geom_bar(aes(y = b), stat = "identity", fill = "cornflowerblue") +

   geom_text(aes(x = a, y = b, label = c), position = position_dodge(width = 0.5), size = 3.5, vjust = 1.0) +

   geom_line(aes(y = c * max_ratio), group = 1, color = "orange", size = 2, alpha = 0.5) +

   geom_point(aes(y = c * max_ratio), color = "red", size = 3, alpha = 0.2) +

   scale_y_continuous(name = "d", sec.axis = sec.axis(~. / max_ratio, name = "e")) +

   geom_text(aes(x = a, y = c * max_ratio, label = c), position = position_dodge(width = 0.5), size = 3.5, vjust = 1.0)+

   theme(axis.title.x = element_blank(), axis.text.x = element_text(angle = 30))