title: Connect mean points of error bars
body: <p>In ggplot2 I'm attempting a simple thing that I just can't get for some reason.  I have adjusted means and SE in a data frame and want to plot the means, error bars and then connect the means with points.  Here's the code and the error (it does everything except connect the means with <code>geom_line</code> (working with <a href="http://wiki.stdout.org/rcookbook/Graphs/Plotting%20means%20and%20error%20bars%20%28ggplot2%29/" rel="nofollow">RCookbook</a>:</p>
  
  <pre><code>library(ggplot2)
  #data set
  data1 &lt;- structure(list(group = structure(1:3, .Label = c("1", "2", "3"
  ), class = "factor"), estimate = c(55.7466654122763, 65.0480954172939, 
  61.9552391704298), SE = c(2.33944612149257, 2.33243565412438, 
  2.33754952927041), t.ratio = c(23.8290016171476, 27.8884844271143, 
  26.5043535525714)), .Names = c("group", "estimate", "SE", "t.ratio"
  ), row.names = c(NA, 3L), class = "data.frame")
  
  #the attempted plot
  pd &lt;- position_dodge(.1)
  ggplot(data1, aes(x=group, y=estimate, group=group)) + 
      geom_errorbar(aes(ymin=estimate-SE, ymax=estimate+SE), 
          colour="black", width=.1, position=pd) +
      geom_line(data=data1, aes(x=group, y=estimate)) + 
      geom_point(position=pd, size=4)
  </code></pre>
  
  <p>the error:</p>
  
  <pre><code>ymax not defined: adjusting position using y instead
  geom_path: Each group consist of only one observation. Do you need to adjust the group aesthetic?
  </code></pre>