Generalize virtualfile_to_gmtgrid to virtualfile_to_data so it works …

…for both grid and dataset

pygmt/clib/session.py

@@ -1648,29 +1648,37 @@ def read_virtualfile(self, vfname):
         return c_read_virtualfile(self.session_pointer, vfname.encode())
 
     @contextmanager
-    def virtualfile_from_gmtgrid(self, grid_pointer):
+    def virtualfile_to_data(self, kind):
         """
-        Create a virtual file for reading a GMT_GRID object.
+        Create a virtual file for writing a GMT data container.
 
-        Parameter
-        ---------
-        grid_pointer : ctp.POINTER(GMT_GRID)
-            Pointer to a GMT_GRID object.
+        Parameters
+        ----------
+        kind : str
+            The kind of data container to create. Choose from "grid" or
+            "dataset".
 
         Yields
         ------
         vfile : str
             Name of the virtual file.
         """
-        family = "GMT_IS_GRID"
-        geometry = "GMT_IS_SURFACE"
-        with self.open_virtual_file(family, geometry, "GMT_IN", grid_pointer) as vfile:
+        family, geometry = {
+            "grid": ("GMT_IS_GRID", "GMT_IS_SURFACE"),
+            "dataset": ("GMT_IS_DATASET", "GMT_IS_PLP"),
+        }[kind]
+        with self.open_virtual_file(family, geometry, "GMT_OUT", None) as vfile:
             yield vfile
 
     @contextmanager
-    def virtualfile_to_gmtgrid(self):
+    def virtualfile_from_gmtgrid(self, grid_pointer):
         """
-        Create a virtual file for writing a GMT_GRID object.
+        Create a virtual file for reading a GMT_GRID object.
+
+        Parameter
+        ---------
+        grid_pointer : ctp.POINTER(GMT_GRID)
+            Pointer to a GMT_GRID object.
 
         Yields
         ------
@@ -1679,7 +1687,7 @@ def virtualfile_to_gmtgrid(self):
         """
         family = "GMT_IS_GRID"
         geometry = "GMT_IS_SURFACE"
-        with self.open_virtual_file(family, geometry, "GMT_OUT", None) as vfile:
+        with self.open_virtual_file(family, geometry, "GMT_IN", grid_pointer) as vfile:
             yield vfile
 
     @contextmanager