title: ggplot2: How to specify multiple fill colors for points that are connected by lines of different colors
body: <p>I am new to <code>ggplot2</code>. I would like to create a line plot that has points on them where the points are filled with different colors than the lines (see the plot below). 
  <img src="https://i.stack.imgur.com/4GqTn.png" alt="enter image description here">
  Suppose the dataset I am working with is the one below:</p>
  
  <pre><code>set.seed(100)
  data&lt;-data.frame(dv=c(rnorm(30), rnorm(30, mean=1), rnorm(30, mean=2)), 
                   iv=rep(1:30, 3), 
                   group=rep(letters[1:3], each=30))
  </code></pre>
  
  <p>I tried the following code:</p>
  
  <pre><code>p&lt;-ggplot(data, aes(x=iv, y=dv, group=group,  pch=group)) + geom_line() + geom_point()
  
  p + scale_color_manual(values=rep("black",3))+ scale_shape(c(19,20,21)) + 
  scale_fill_manual(values=c("blue", "red","gray"))
  
  p +  scale_shape(c(19,20,21)) + scale_fill_manual(values=c("blue", "red","gray"))
  </code></pre>
  
  <p>But I do not get what I want.I hope someone can point me to the right direction. Thanks!</p>