title: Drawing outlines around multiple geom_point groups with ggplot
body: <p>I currrently have the code included below to draw this:
  <img src="https://i.stack.imgur.com/hLAnV.png" alt="enter image description here"></p>
  
  <p>What I am trying to do is get the outline for each of the groups to follow all of the points in each group - rather than skip some of them as it currently does. In addition I would want each outline to have a semi-transparent fill. Thanks for any help.  </p>
  
  <pre><code>library(ggplot2)
  library(reshape)
  library(car)
  
  G1 &lt;- 1:10
  G2 &lt;- 11:20
  G3 &lt;- 21:30
  G4 &lt;- 31:35
  G5 &lt;- 36:41
  
  sdata &lt;- read.csv("http://dl.dropbox.com/u/58164604/sdata.csv", stringsAsFactors = FALSE)
  pdata&lt;-melt(sdata, id.vars="Var")
  
  VarArea &lt;- data.frame(unique(pdata$Var))
  VarFinalMin &lt;-c()
  for (g in 1:max(VarArea))
  {
  VarNum&lt;-pdata[which(pdata$Var==g),1:c(ncol(pdata))]
  VarN &lt;- g
  VarMin &lt;- min(VarNum$value)
  VarMinN &lt;- cbind(VarN, VarMin)
  VarFinalMin &lt;- rbind(VarFinalMin,VarMinN) 
  }
  VFinalMin &lt;- data.frame(VarFinalMin)
  colnames(VFinalMin)&lt;-c("Variable", "Value")
  
  VarFinalMax &lt;-c()
  for (g in 1:max(VarArea))
  {
  VarNum&lt;-pdata[which(pdata$Var==g),1:c(ncol(pdata))]
  VarN &lt;- g
  VarMax &lt;- max(VarNum$value)
  VarMaxN &lt;- cbind(VarN, VarMax)
  VarFinalMax &lt;- rbind(VarFinalMax,VarMaxN)
  }
  VFinalMax &lt;- data.frame(VarFinalMax)
  colnames(VFinalMax)&lt;-c("Variable", "Value")
  
  VFinal&lt;-rbind(VFinalMin, VFinalMax)
  VFinal$Group &lt;- recode(VFinal$Variable, "G1 = 'A'; G2 = 'B'; G3 = 'C'; G4 = 'D'; G5 = 'E'")
  
  ggplot(VFinal, aes(Variable, Value, colour = Group)) + geom_point()
  find_hull &lt;- function(VFinal) VFinal[chull(VFinal$Variable, VFinal$Value), ]
  hulls &lt;- ddply(VFinal, "Group", find_hull)
  ggplot(VFinal, aes(Variable, Value, colour = Group)) + geom_point() + geom_polygon(data = hulls, fill = NA)
  </code></pre>