title: ggplot2, fitting data with log2 or log10 doesn't affect the plot
body: <p>I wanted a display a geom_smooth with a natural log   and this code works fine: </p>
  
  <pre><code>    df &lt;- iris
  iris_logplot &lt;- ggplot(df, aes(Sepal.Length, Sepal.Width, colour = Species))
  
  iris_logplot + stat_summary(fun.y =median, geom = "point") + stat_summary(fun.data = mean_cl_boot, aes(group = Species), geom = "errorbar", width = 0.2) + 
    geom_smooth(method="lm", formula=y~log(x)) 
  </code></pre>
  
  <p>now I want to display a geom_smooth with a log whose base is 2 and I apply this code: </p>
  
  <pre><code>df &lt;- iris
  iris_logplot &lt;- ggplot(df, aes(Sepal.Length, Sepal.Width, colour = Species))
  
  iris_logplot + stat_summary(fun.y =median, geom = "point") +
    stat_summary(fun.data = mean_cl_boot, aes(group = Species), geom = "errorbar", width = 0.2) + geom_smooth(method="lm", formula=y~log2(x)) 
  </code></pre>
  
  <p>Why the  plots are the same? </p>
  
  <p>Thanks </p>