title: Using colormap with bokeh scatter
body: <p>In <code>matplotlib</code> the <a href="http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.scatter" rel="noreferrer">scatterplot</a> offers the possibility of using the color of a plot to indicate value or magnitude like this plot:</p>
  
  <p><a href="https://i.stack.imgur.com/1bWo8.png" rel="noreferrer"><img src="https://i.stack.imgur.com/1bWo8.png" alt="enter image description here"></a></p>
  
  <p>For <code>bokeh</code>, similar <a href="http://bokeh.pydata.org/en/latest/docs/gallery/color_scatter.html" rel="noreferrer">examples</a> seem to manually generate the rgb colors, which makes it difficult to produce plots with color scaled by magnitude, esp. wrt. diverging colormaps.</p>
  
  <p>Is it possible to have similar functionality in <code>bokeh</code>, or to use <code>matplotlib</code> colormaps to set the color?</p>