title: How do I plot contours on top of a hexbin plot?
body: <p>I have two arrays, <code>x</code> and <code>y</code>, both with values within a well defined range. I am able to create a hexbin plot (<a href="http://goo.gl/NBUQA" rel="noreferrer">see image</a>), however, I would now like to normalize these distributions and draw contour plots around them. I am not so interested in the counts within each hexbin. Instead I am interested in showing the contours corresponding to 1, 2 and 3 standard deviations (σ). I hope to have an output showing the contours similar to <a href="http://matplotlib.sourceforge.net/examples/pylab_examples/tricontour_vs_griddata.html" rel="noreferrer">this</a> example. The distribution is Gaussian. I would greatly appreciate any input on this.</p>