Speed up step lookup when no step

scottshambaugh · scottshambaugh · commit d8471f9f2fe0 · 2026-02-02T15:13:18.000-07:00
Fix tests
diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
@@ -1691,7 +1691,7 @@ def pts_to_midstep(x, *args):
     return steps
 
 
-STEP_LOOKUP_MAP = {'default': lambda x, y: (x, y),
+STEP_LOOKUP_MAP = {'default': None,  # Sentinel: use xy unchanged
                    'steps': pts_to_prestep,
                    'steps-pre': pts_to_prestep,
                    'steps-post': pts_to_poststep,
diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
@@ -1559,7 +1559,8 @@ def _make_verts_for_region(self, t, f1, f2, idx0, idx1):
         f2_slice = f2[idx0:idx1]
         if self._step is not None:
             step_func = cbook.STEP_LOOKUP_MAP["steps-" + self._step]
-            t_slice, f1_slice, f2_slice = step_func(t_slice, f1_slice, f2_slice)
+            if step_func is not None:
+                t_slice, f1_slice, f2_slice = step_func(t_slice, f1_slice, f2_slice)
 
         if self._interpolate:
             start = self._get_interpolating_points(t, f1, f2, idx0)
diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
@@ -709,9 +709,15 @@ def recache(self, always=False):
             interpolation_steps = self._path._interpolation_steps
         else:
             interpolation_steps = 1
-        xy = STEP_LOOKUP_MAP[self._drawstyle](*self._xy.T)
-        self._path = Path(np.asarray(xy).T,
-                          _interpolation_steps=interpolation_steps)
+        step_func = STEP_LOOKUP_MAP[self._drawstyle]
+        if step_func is None:
+            vertices = self._xy
+        else:
+            steps = step_func(*self._xy.T)
+            vertices = np.empty((steps.shape[1], 2))
+            vertices[:, 0] = steps[0]
+            vertices[:, 1] = steps[1]
+        self._path = Path(vertices, _interpolation_steps=interpolation_steps)
         self._transformed_path = None
         self._invalidx = False
         self._invalidy = False
@@ -724,8 +730,15 @@ def _transform_path(self, subslice=None):
         """
         # Masked arrays are now handled by the Path class itself
         if subslice is not None:
-            xy = STEP_LOOKUP_MAP[self._drawstyle](*self._xy[subslice, :].T)
-            _path = Path(np.asarray(xy).T,
+            step_func = STEP_LOOKUP_MAP[self._drawstyle]
+            if step_func is None:
+                vertices = self._xy[subslice]
+            else:
+                steps = step_func(*self._xy[subslice, :].T)
+                vertices = np.empty((steps.shape[1], 2))
+                vertices[:, 0] = steps[0]
+                vertices[:, 1] = steps[1]
+            _path = Path(vertices,
                          _interpolation_steps=self._path._interpolation_steps)
         else:
             _path = self._path
