ENH: density property for SparseSeries #2384

RELEASE.rst

@@ -36,6 +36,7 @@ pandas 0.10.0
     for both Series and DataFrame (#2002)
   - Add ``duplicated`` and ``drop_duplicates`` functions to Series (#1923)
   - Add docs for ``HDFStore table`` format
+  - 'density' property in `SparseSeries` (#2384)
 
 **API Changes**
 

doc/source/v0.10.0.txt

@@ -26,7 +26,7 @@ Updated PyTables Support
        store = HDFStore('store.h5')
        df = DataFrame(randn(8, 3), index=date_range('1/1/2000', periods=8),
                   columns=['A', 'B', 'C'])
-       df 
+       df
 
        # appending data frames
        df1 = df[0:4]
@@ -66,17 +66,18 @@ Updated PyTables Support
        - added mixed-dtype support!
 
           .. ipython:: python
-            
+
              df['string'] = 'string'
 	     df['int']    = 1
-            
+
              store.append('df',df)
-	     df1 = store.select('df')	    
+	     df1 = store.select('df')
 	     df1
 	     df1.get_dtype_counts()
 
        - performance improvments on table writing
        - support for arbitrarily indexed dimensions
+	   - ``SparseSeries`` now has a ``density`` property (#2384)
 
   **Bug Fixes**
 

pandas/sparse/series.py

@@ -372,6 +372,10 @@ def to_dense(self, sparse_only=False):
         else:
             return Series(self.values, index=self.index, name=self.name)
 
+    @property
+    def density(self):
+        return float(len(self.sp_index)) / len(self.index)
+
     def astype(self, dtype=None):
         """
 

pandas/sparse/tests/test_sparse.py

@@ -838,6 +838,10 @@ def test_dense_to_sparse(self):
         self.assertEquals(sdf.default_fill_value, 0)
         tm.assert_frame_equal(sdf.to_dense(), df)
 
+    def test_density(self):
+        df = SparseSeries([nan, nan, nan, 0, 1, 2, 3, 4, 5, 6])
+        self.assertEquals(df.density, 0.7)
+
     def test_sparse_to_dense(self):
         pass