Merge pull request #81 from pmk21/neg-reduce

Support for negative reduce

fast_carpenter/define/reductions.py

@@ -21,7 +21,7 @@ def __init__(self, index, fill_missing, force_float=True):
                 self.dtype = float
 
     def __call__(self, array):
-        mask = array.counts > self.index
+        mask = array.counts > abs(self.index)
         output = np.full(len(array), self.fill_missing, dtype=self.dtype)
         output[mask] = array[mask, self.index]
         return output