title: specifying number of breaks with scales in ggplot2 without a transform?
body: <p>If I want my data axis to have more breaks but without a transformation on the values, how can I do it in ggplot2? eg:</p>
  
  <pre><code>... + scale_x_continuous(breaks=scales.trans_breaks("log2", function(x) 2^x, n=8),   limits=limits)
  </code></pre>
  
  <p>works if you want your data transformed and the <code>n=</code> parameter lets you say how many breaks. How can you specify breaks without transforming the data? Do you just give it an identity function? </p>