BUG adding support for dense Series in the SparseDataFrame constructor, and providing useful error messages for other types (#19374) (#19377)

Author: datapythonista

doc/source/whatsnew/v0.23.0.txt

@@ -512,7 +512,7 @@ Groupby/Resample/Rolling
 Sparse
 ^^^^^^
 
--
+- Bug in which creating a ``SparseDataFrame`` from a dense ``Series`` or an unsupported type raised an uncontrolled exception (:issue:`19374`)
 -
 -
 

pandas/core/sparse/frame.py

@@ -95,6 +95,9 @@ def __init__(self, data=None, index=None, columns=None, default_kind=None,
                                  dtype=dtype, copy=copy)
         elif isinstance(data, DataFrame):
             mgr = self._init_dict(data, data.index, data.columns, dtype=dtype)
+        elif isinstance(data, Series):
+            mgr = self._init_dict(data.to_frame(), data.index,
+                                  columns=None, dtype=dtype)
         elif isinstance(data, BlockManager):
             mgr = self._init_mgr(data, axes=dict(index=index, columns=columns),
                                  dtype=dtype, copy=copy)
@@ -116,6 +119,10 @@ def __init__(self, data=None, index=None, columns=None, default_kind=None,
             mgr = to_manager(data, columns, index)
             if dtype is not None:
                 mgr = mgr.astype(dtype)
+        else:
+            msg = ('SparseDataFrame called with unkown type "{data_type}" '
+                   'for data argument')
+            raise TypeError(msg.format(data_type=type(data).__name__))
 
         generic.NDFrame.__init__(self, mgr)
 

pandas/tests/sparse/frame/test_frame.py

@@ -199,6 +199,29 @@ def test_constructor_from_series(self):
         # without sparse value raises error
         # df2 = SparseDataFrame([x2_sparse, y])
 
+    def test_constructor_from_dense_series(self):
+        # GH 19393
+        # series with name
+        x = Series(np.random.randn(10000), name='a')
+        result = SparseDataFrame(x)
+        expected = x.to_frame().to_sparse()
+        tm.assert_sp_frame_equal(result, expected)
+
+        # series with no name
+        x = Series(np.random.randn(10000))
+        result = SparseDataFrame(x)
+        expected = x.to_frame().to_sparse()
+        tm.assert_sp_frame_equal(result, expected)
+
+    def test_constructor_from_unknown_type(self):
+        # GH 19393
+        class Unknown:
+            pass
+        with pytest.raises(TypeError,
+                           message='SparseDataFrame called with unkown type '
+                                   '"Unknown" for data argument'):
+            SparseDataFrame(Unknown())
+
     def test_constructor_preserve_attr(self):
         # GH 13866
         arr = pd.SparseArray([1, 0, 3, 0], dtype=np.int64, fill_value=0)