title: Pattern fill for stacked area plot using ggplot2 in R
body: <p>I'm trying to develop a stacked area plot with a combination of colors and patterns. I know R is a bit limited when it comes to pattern fills. I tried looking up, but could only find <code>patternplot</code> which is limited to bar and pie charts. Any help is much appreciated!</p>
  
  <p>Details on the data:
  There are four phases given by P1, P2, P3 and P4. Each phase is followed by a clearance (C). The y-axis is the probability (y-axis) 
   of each phase and its corresponding clearances across a time (0 to 5 seconds) on the x-axis. The phases will be in solid color, whereas the clearance will be a 45 degree hash pattern. The color of the clearance pattern follows the corresponding phase. For example, in below fig, P1 is solid gray, so the clearances P1_C and will hashed with gray color and so on.</p>
  
  <p>Data and current progress: </p>
  
  <pre><code>mydat= data.frame("1"=c(1,0,0,0,0,0,0,0), "2"=c(0,0.9,0.1,0,0,0,0,0),
  "3"=c(0,0,1,0,0,0,0,0), "4"=c(0,0,0,0.6,0.25,0.15,0,0),
  "5"=c(0,0,0,0,0,0.25,0.75,0), "6"=c(0.1,0,0,0,0,0,0,0.9))
  rownames(mydat)=c("P1","P1_C","P2","P2_C","P3","P3_C","P4","P4_C")
  colnames(mydat)=seq(0,5,1)
  mydat=t(mydat)
  mydat=mydat[,c(8,7,6,5,4,3,2,1)]
  melted = melt(mydat, 1)
  colnames(melted)=c("time","Phase","Probability")
  
  ggplot(melted, aes(x = time, y = Probability, fill=Phase)) +
   geom_area()+
   scale_fill_manual(values=c("NA","deepskyblue","NA","darkblue","NA","lightgreen","NA","gray"))+
   scale_x_continuous("Time",limits=c(0,5), breaks = c(seq(0,5,1)),expand = c(0,0)) +
   scale_y_continuous("Probability", breaks = c(seq(0,1,0.1)), expand = c(0,0)) +
   coord_cartesian(ylim = c(0,1))+
   theme_bw()
  </code></pre>
  
  <p>Currently, I have the clearance set to <code>NA</code>, but eventually I'd like the final plot to be as shown below. Thanks!</p>
  
  <p><a href="https://i.stack.imgur.com/8OdzG.png" rel="nofollow noreferrer">Required Plot</a></p>