BUG: Set fill_value and ndim parameter in make_block when generating SparseBlock from result

Author: Licht-T

pandas/core/internals.py

@@ -1388,6 +1388,11 @@ def where(self, other, cond, align=True, raise_on_error=True,
         if hasattr(other, 'reindex_axis'):
             other = other.values
 
+        if is_scalar(other) or is_list_like(other):
+            fill_value = other
+        else:
+            fill_value = None
+
         if hasattr(cond, 'reindex_axis'):
             cond = cond.values
 
@@ -1446,7 +1451,12 @@ def func(cond, values, other):
             if try_cast:
                 result = self._try_cast_result(result)
 
-            return self.make_block(result)
+            if isinstance(result, np.ndarray):
+                ndim = result.ndim
+            else:
+                ndim = None
+
+            return self.make_block(result, ndim=ndim, fill_value=fill_value)
 
         # might need to separate out blocks
         axis = cond.ndim - 1