title: Combine legends for color and shape into a single legend
body: <p>I'm creating a plot in ggplot from a 2 x 2 study design and would like to use 2 colors and 2 symbols to classify my 4 different treatment combinations.  Currently I have 2 legends, one for the colors and one for the two shapes.  How can I combine them into a single legend so I have one blue circle, one red circle, one blue triangle, and one read triangle?</p>
  
  <p>Some data:</p>
  
  <pre><code>state1 &lt;- c(rep(c(rep("N", 7), rep("Y", 7)), 2))
  year &lt;- rep(c(2003:2009), 4)
  group1 &lt;- c(rep("C", 14), rep("E", 14))
  group2 &lt;- paste(state1, group1, sep = "")
  beta &lt;- c(0.16,0.15,0.08,0.08,0.18,0.48,0.14,0.19,0.00,0.00,0.04,0.08,0.27,0.03,0.11,0.12,0.09,0.09,0.10,0.19,0.16,0.00,0.11,0.07,0.08,0.09,0.19,0.10)
      lcl &lt;- c(0.13,0.12,0.05,0.05,0.12,0.35,0.06,0.13,0.00,0.00,0.01,0.04,0.20,0.00,0.09,0.09,0.06,0.06,0.07,0.15,0.11,0.00,0.07,0.03,0.05,0.06,0.15,0.06)
      ucl &lt;- c(0.20,0.20,0.13,0.14,0.27,0.61,0.28,0.27,0.00,1.00,0.16,0.16,0.36,0.82,0.14,0.15,0.13,0.13,0.15,0.23,0.21,0.00,0.15,0.14,0.12,0.12,0.23,0.16)
  data &lt;- data.frame(state1,year,group1,group2,beta,lcl,ucl)
  </code></pre>
  
  <p>Plot:</p>
  
  <pre><code>library(ggplot2)
  pd &lt;- position_dodge(.65)
  ggplot(data = data, aes(x = year, y = beta, colour = state1, group = group2, shape = group1)) +
    geom_point(position = pd, size = 4) +
    geom_errorbar(aes(ymin = lcl, ymax = ucl),colour = "black", width = 0.5, position = pd) +
    scale_colour_hue(name = "Treatment &amp; State",  #Legend label, use darker colors
                     labels = c("Control", "Exclosure"),
                     l = 40) +
    scale_shape(name = "State", labels = c("Non-F", "Flwr"))
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Kitw2.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Kitw2.png" alt="enter image description here"></a></p>