add tim's suggestion

lib/matplotlib/axes/_axes.py

@@ -8350,10 +8350,10 @@ def matshow(self, Z, **kwargs):
 
     @_api.make_keyword_only("3.9", "vert")
     @_preprocess_data(replace_names=["dataset"])
-    def violinplot(self, dataset, positions=None, vert=None, widths=0.5,
-                   showmeans=False, showextrema=True, showmedians=False,
-                   quantiles=None, points=100, bw_method=None, side='both',
-                   orientation=None):
+    def violinplot(self, dataset, positions=None, orientation='vertical',
+                   vert=None, widths=0.5, showmeans=False, showextrema=True,
+                   showmedians=False, quantiles=None, points=100,
+                   bw_method=None, side='both',):
         """
         Make a violin plot.
 
@@ -8475,9 +8475,9 @@ def _kde_method(X, coords):
                            showmedians=showmedians, side=side)
 
     @_api.make_keyword_only("3.9", "vert")
-    def violin(self, vpstats, positions=None, vert=None, widths=0.5,
-               showmeans=False, showextrema=True, showmedians=False, side='both',
-               orientation=None):
+    def violin(self, vpstats, positions=None, orientation=None,
+               vert=None, widths=0.5, showmeans=False, showextrema=True,
+               showmedians=False, side='both'):
         """
         Draw a violin plot from pre-computed statistics.
 
@@ -8599,23 +8599,17 @@ def violin(self, vpstats, positions=None, vert=None, widths=0.5,
         datashape_message = ("List of violinplot statistics and `{0}` "
                              "values must have the same length")
 
+        # vert and orientation parameters are linked until vert's
+        # deprecation period expires. If both are selected,
+        # vert takes precedence.
         if vert is not None:
             _api.warn_deprecated(
                 "3.10",
                 name="vert: bool",
                 alternative="orientation: {'vertical', 'horizontal'}"
-            )
-
-        # vert and orientation parameters are linked until vert's
-        # deprecation period expires. If both are selected,
-        # vert takes precedence.
-        if vert or vert is None and orientation is None:
-            orientation = 'vertical'
-        elif vert is False:
-            orientation = 'horizontal'
-
-        if orientation is not None:
-            _api.check_in_list(['horizontal', 'vertical'], orientation=orientation)
+                )
+            orientation = 'vertical' if vert else 'horizontal'
+        _api.check_in_list(['horizontal', 'vertical'], orientation=orientation)
 
         # Validate positions
         if positions is None: