title: Gradient of n colors ranging from color 1 and color 2
body: <p>I often work with <code>ggplot2</code> that makes gradients nice (<a href="http://www.r-bloggers.com/ggtutorial-day-5-gradient-colors-and-brewer-palettes/" rel="noreferrer">click here for an example</a>).  I have a need to work in base and I think <code>scales</code> can be used there to create color gradients as well but I'm severely off the mark on how.  The basic goal is generate a palette of n colors that ranges from x color to y color.  The solution needs to work in base though.  This was a starting point but there's no place to input an n.  </p>
  
  <pre><code> scale_colour_gradientn(colours=c("red", "blue"))
  </code></pre>
  
  <p>I am well aware of:</p>
  
  <pre><code>brewer.pal(8, "Spectral") 
  </code></pre>
  
  <p>from <code>RColorBrewer</code>.  I'm looking more for the approach similar to how <code>ggplot2</code> handles gradients that says I have these two colors and I want 15 colors along the way.  How can I do that?</p>