title: lattice in R- line types
body: <p>I have a lattice xyplot with smoothed lines (6 different lines). I would like to change the line types- color and type of line (dashed, etc), so that they are understandable in B&amp;W, rather than in color (which is the default). Can anyone provide advice on this? Below is my current code: </p>
  
  <pre><code>xyplot(y~x,
   data=df,
   group=categorical,
   type = "smooth",
   ylim=c(-2,0.5),
   xlab="x",
   ylab="y",
   auto.key=list(space="top",
   columns=3,
   title="",
   cex.title=0.1,
   lines=FALSE, points=TRUE)
  )
  </code></pre>
  
  <p>Thank you</p>