title: label over stat_function ggplot
body: <p>I'm using ggplot2 on R and I'm trying to plot some functions. The thing is I'm trying to add a label over the colorful plot generated with  stat_function. </p>
  
  <p>The only thing I found was to add the color on the legend, but I need to add the label over the functions not in the legend ( for the sake of my work ).</p>
  
  <p>A sample code is provided below</p>
  
  <pre><code>library(ggplot2)
  f &lt;- ggplot(data.frame(x = c(0, 10)), aes(x))
  f + stat_function(fun = sin, colour = "red") +
  stat_function(fun = cos, colour = "blue")
  </code></pre>
  
  <p>Thank you in advance</p>