title: Problems with legend display using geom_pointrange in ggplot2
body: <p>I am using ggplot2 with geom_pointrange in R to plot the sensitivity (95% CI) of five groups under six scenarios (in total, 30 plots of sensitivity). The six scenarios are derived from a 3x2 set of scenarios. I can plot the graph successfully, but I am having problems with the legend. I have used three different colours and solid and dashed lines to represent the six scenarios. However, I am unable to display the dashed lines on the legend (only the three colours, each of which repeats twice). Initially I had used six different colours, but colleagues have asked me to change this.</p>
  
  <p>I have used geom_pointrange within ggplot2, but have had problems getting the legend to display properly:</p>
  
  <pre><code>sens &lt;- cbind.data.frame(
    group = rep(c("Grp1", "Grp2", "Grp3", "Grp4", "Grp5"), 6),
    mean  = c(0.70, 0.70, 0.65, 0.60, 0.72, 0.85, 0.84, 0.77, 0.68, 0.77,
              0.71, 0.71, 0.69, 0.65, 0.76, 0.90, 0.88, 0.82, 0.82, 0.87,
              0.78, 0.78, 0.79, 0.73, 0.83, 0.92, 0.92, 0.92, 0.90, 0.93) * 100, 
    lower = c(0.64, 0.64, 0.59, 0.55, 0.68, 0.73, 0.73, 0.65, 0.55, 0.68,
              0.66, 0.66, 0.63, 0.59, 0.72, 0.80, 0.78, 0.70, 0.70, 0.79,
              0.73, 0.72, 0.74, 0.68, 0.80, 0.84, 0.84, 0.82, 0.79, 0.87) * 100,
    upper = c(0.75, 0.75, 0.70, 0.66, 0.76, 0.92, 0.91, 0.87, 0.80, 0.84,
              0.77, 0.76, 0.74, 0.70, 0.79, 0.95, 0.94, 0.90, 0.90, 0.92,
              0.82, 0.82, 0.83, 0.79, 0.86, 0.97, 0.97, 0.97, 0.96, 0.97) * 100,
    type = rep(c("A1&amp;B1", "A1&amp;B2", "A2&amp;B1", "A2&amp;B2", "A3&amp;B1", "A3&amp;B2"), each=5),
    type2 = rep(c(rep("B1", 5), rep("B2", 5)), 3),
    type3 = rep(c(rep("A1", 10), rep("A2", 10), rep("A3", 10))))
  
  
  ggplot(sens, aes(group, mean, colour = type, group = type, linetype = type)) +
    geom_pointrange(aes(ymin = lower, ymax = upper), position = position_dodge(width = 0.5), size=1.25) + 
    coord_flip() +  
    xlab("Group") + 
    ylab("Sensitivity (95% CI)") +
    scale_color_manual(values = c("red", "red", "dark grey", "dark grey", "blue", "blue")) + 
    scale_linetype_manual(values=c(1,2,1,2,1,2)) +
    theme(axis.text.x=element_text(size=15, vjust=0.5, color = 'black'),  # x-axis labels
          axis.text.y=element_text(size=15, vjust=0.5, color = 'black'),  # y-axis labels
          axis.title.x=element_text(size=17.5, vjust=0.1),                # x-title justification  
          axis.title.y=element_text(size=17.5, vjust=1.5),                 # y-title justification
          legend.title=element_blank(),
          legend.position= "bottom",       
          legend.text = element_text(size = 14.5) 
    )
  </code></pre>
  
  <p>I wish to see a legend with six distinct labels (3 different colours x 2 different linetypes).</p>