title: Labelling and theme of ggalluvial plot in R
body: <p>For the past hours I have tried to understand the whole design/theme/labelling concept around <em>ggalluvial</em>, but I failed.
  Within minutes I was able to produce the kind of graph I want (thanks to the package ggalluvial), but I can't figure how to produce the correct labelling/theme I'd like to have.</p>
  
  <p>This is where I am currently:
  <a href="https://i.stack.imgur.com/LnHXW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LnHXW.png" alt="Almost Done!"></a></p>
  
  <p>This is where I was initially:
  <a href="https://i.stack.imgur.com/qXWBL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qXWBL.png" alt="white labels"></a></p>
  
  <p>To get you to understand where I am, here's a reproducible example</p>
  
  <p><a href="https://i.stack.imgur.com/obkOO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/obkOO.png" alt="Titanic Alluvial"></a></p>
  
  <p>I used the following code:</p>
  
  <pre><code>library(ggalluvial)
  
  ds &lt;- as.data.frame(Titanic)
  
  ggplot(ds,
     aes(weight = Freq, axis1 = Sex, axis2 = Class)) +
  geom_alluvium(aes(fill = Sex), width = 1/12) +
  geom_stratum(width = 1/4, fill = "black", color = "grey") + 
  scale_x_continuous(breaks = 1:2, labels = c("Sex", "Class")) + 
  scale_fill_manual(name = "", values=c("#A0A0A0", "#494949")) +              
  ggtitle("Titanic Survival") +                            
  theme_bw() +                                                          
  geom_text(stat = "stratum", color="white",label.strata = TRUE,
          angle=c(90,90,0,0,0,0) , size=6, 
          nudge_y=c(1,2,3,4,5,0)) +
  theme(legend.position = "bottom",
      title = element_text(size = 20),
      legend.text = element_text(size = 20),
      axis.text.y = element_blank(),
      axis.text.x = element_text(size=20))
  </code></pre>
  
  <p>What I would like to change:</p>
  
  <ul>
  <li>turn labels on the left vertically
  
  <ul>
  <li><em>done</em></li>
  </ul></li>
  <li>make labels on the right not overlap (not visible with the Titanic data)
  
  <ul>
  <li><em>I tried nudging. But it may be more useful to place these legends outside the graph, maybe like on an axis?</em></li>
  </ul></li>
  <li>remove y-axis labels
  
  <ul>
  <li><em>done</em></li>
  </ul></li>
  <li>Understand with what command I can change each of the text elements size (title, legend, labels, axis labels)
  
  <ul>
  <li><em>dome</em></li>
  </ul></li>
  </ul>
  
  <p>I am very happy for any help on this. Thank you.</p>