title: Binning with zero values in pandas
body: <p>I have a series of 633 values, ~50% of which are 0. Ideally, I'd like to bin my values (for choropleth mapping purposes) using <code>qcut()</code>, but that gives me an error due to non-unique bin edges.
  What's the best way to separate the data, quantile the non-zero values, and then recombine them into a single column such that zero values have a value of 0, and quantiled values have <code>categorical.label + 1</code>?</p>