title: How to change the color legend in fine granularity using ggplot2
body: <p>I am very new to ggplot2 and trying to create 9 geom tile plots using this melted <a href="http://dl.dropboxusercontent.com/u/7147744/cm_melted.log" rel="nofollow noreferrer">dataset</a> and the below code</p>
  
  <pre><code>cm &lt;- read.table("http://dl.dropboxusercontent.com/u/7147744/cm_melted.log", header=T, sep=" ")
  xlab = expression(italic(lb)~(Normalised))
  ylab = expression(italic(dti)~(Normalised))
  
  ggplot(cm, aes(x=LB, y=DTI)) +
    facet_wrap(~Method, ncol=3) +
    geom_tile(aes(fill=CM), colour="white") +
    scale_fill_gradient(low="white", high="steelblue") +   
    theme_bw() +
    coord_equal() +
    xlab(xlab) +
    ylab(ylab) +
    ggtitle("Comparison of different methods based on composite metric")
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/qDlGd.png" alt=""></p>
  
  <p>I would like to change the colors of the tiles and the legend in more fine granularity. For example if the minimum value of <code>CM</code> is 0 and maximum is 1, then the legend and tiles should be made up from 11 different colors for 0.1 step size.</p>
  
  <p>Another concern is how can I turn the title color for the NA values in `CM' into white so that the main focus is only with the lower triangle.</p>
  
  <p>And the last thing is can I use black and white pattern fills for these plots? Or any other suitable suggestions for print quality plots in bw.</p>
  
  <p>Many thanks.</p>
  
  <p><strong>Update1:</strong></p>
  
  <p>while using <code>geom_tile(aes(fill=factor(value), colour="white")) +</code> I can get the below plot as it is color coded based on every distinct value of <code>CM</code></p>
  
  <p><img src="https://i.stack.imgur.com/buCS7.png" alt=""></p>