title: Aligning multiple plot in egg::ggarrange
body: <p>I'm making a multiplot with egg::ggarrange for 5 figures. I'm wondering how can I aligning plot area of b,d and c,e in vertical position?</p>
  
  <p><strong>PS: Figure b and c have to be in different decimal in y axis.</strong></p>
  
  <pre><code>    library(egg)
      library(ggplot2)
  
      data("ToothGrowth")
      data("mtcars")
  
      P1 &lt;- ggplot(mtcars, aes(x = wt, y = mpg, color=cyl))+
            geom_point()       # Add correlation coefficient
  
      P2 &lt;- ggboxplot(ToothGrowth, x = "dose", y = "len",
               color = "dose", palette = "jco")+
               scale_y_continuous(breaks=c(10.5, 20.5, 30.5))
  
      P3 &lt;- ggdotplot(ToothGrowth, x = "dose", y = "len",
               color = "dose", palette = "jco", binwidth = 1)
  
  
      ggarrange(P1,
          ggarrange(P2, P2, ncol = 2, labels = c("b", "d"), align = "h",widths = c(1.5,2)), 
          ggarrange(P3, P3, ncol = 2, labels = c("c", "e"), align = "h",widths = c(1.5,2)), 
        nrow = 3, 
        heights = c(1.5, 1, 1),
        labels = "a" 
        ) 
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/KqbZu.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/KqbZu.png" alt="enter image description here"></a></p>