Deprecate QuadContourSet.allsegs, .allkinds, .tcolors, .tlinewidths.

anntzer · anntzer · commit ba55c525a140 · 2023-02-03T00:17:59.000+01:00
Directly construct the relevant path objects and the collections with
the right properties instead of carrying around another copy of the
information in raw array form.  By having fewer intermediate objects
lying around for a long time (as attributes of the QuadContourSet) this
makes the logic easier to follow.
diff --git a/doc/api/next_api_changes/deprecations/25138-AL.rst b/doc/api/next_api_changes/deprecations/25138-AL.rst
@@ -0,0 +1,5 @@
+``allsegs``, ``allkinds``, ``tcolors`` and ``tlinewidths`` attributes of `.ContourSet`
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+These attributes are deprecated; if required, directly retrieve the vertices
+and codes of the Path objects in ``QuadContourSet.collections`` and the colors
+and the linewidths of these collections.
diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
@@ -774,8 +774,8 @@ def add_lines(self, *args, **kwargs):
             # TODO: Make colorbar lines auto-follow changes in contour lines.
             return self.add_lines(
                 CS.levels,
-                [c[0] for c in CS.tcolors],
-                [t[0] for t in CS.tlinewidths],
+                CS.to_rgba(CS.cvalues, CS.alpha),
+                [coll.get_linewidths()[0] for coll in CS.collections],
                 erase=erase)
         else:
             self, levels, colors, linewidths, erase = params.values()
diff --git a/lib/matplotlib/contour.py b/lib/matplotlib/contour.py
@@ -3,7 +3,6 @@
 """
 
 import functools
-import itertools
 from numbers import Integral
 
 import numpy as np
@@ -767,6 +766,10 @@ def __init__(self, ax, *args,
             self.negative_linestyles = \
                 mpl.rcParams['contour.negative_linestyle']
 
+        # The base class _process_args will update _allpaths, which gets picked
+        # up by _get_allpaths below.  OTOH the _process_args of subclasses
+        # leave _allpaths as None and instead set _contour_generator.
+        self._allpaths = None
         kwargs = self._process_args(*args, **kwargs)
         self._process_levels()
 
@@ -820,23 +823,7 @@ def __init__(self, ax, *args,
             self.norm.vmax = vmax
         self._process_colors()
 
-        if getattr(self, 'allsegs', None) is None:
-            self.allsegs, self.allkinds = self._get_allsegs_and_allkinds()
-        elif self.allkinds is None:
-            # allsegs specified in constructor may or may not have allkinds as
-            # well.  Must ensure allkinds can be zipped below.
-            self.allkinds = [None] * len(self.allsegs)
-
-        # Each entry in (allsegs, allkinds) is a list of (segs, kinds) which
-        # specifies a list of Paths: segs is a list of (N, 2) arrays of xy
-        # coordinates, kinds is a list of arrays of corresponding pathcodes.
-        # However, kinds can also be None; in which case all paths in that list
-        # are codeless.
-        allpaths = [
-            [*map(mpath.Path,
-                  segs,
-                  kinds if kinds is not None else itertools.repeat(None))]
-            for segs, kinds in zip(self.allsegs, self.allkinds)]
+        allpaths = self._get_allpaths()
 
         if self.filled:
             if self.linewidths is not None:
@@ -857,7 +844,7 @@ def __init__(self, ax, *args,
                 for level, level_upper, paths
                 in zip(lowers, uppers, allpaths)]
         else:
-            self.tlinewidths = tlinewidths = self._process_linewidths()
+            tlinewidths = self._process_linewidths()
             tlinestyles = self._process_linestyles()
             aa = self.antialiased
             if aa is not None:
@@ -895,6 +882,15 @@ def __init__(self, ax, *args,
                 ", ".join(map(repr, kwargs))
             )
 
+    allsegs = _api.deprecated("3.8", pending=True)(property(lambda self: [
+        p.vertices for c in self.collections for p in c.get_paths()]))
+    allkinds = _api.deprecated("3.8", pending=True)(property(lambda self: [
+        p.codes for c in self.collections for p in c.get_paths()]))
+    tcolors = _api.deprecated("3.8")(property(lambda self: [
+        (tuple(rgba),) for rgba in self.to_rgba(self.cvalues, self.alpha)]))
+    tlinewidths = _api.deprecated("3.8")(
+        property(lambda self: self._process_linewidths()))
+
     def get_transform(self):
         """Return the `.Transform` instance used by this ContourSet."""
         if self._transform is None:
@@ -979,51 +975,60 @@ def _process_args(self, *args, **kwargs):
         Must set self.levels, self.zmin and self.zmax, and update axes limits.
         """
         self.levels = args[0]
-        self.allsegs = args[1]
-        self.allkinds = args[2] if len(args) > 2 else None
+        allsegs = args[1]
+        allkinds = args[2] if len(args) > 2 else None
         self.zmax = np.max(self.levels)
         self.zmin = np.min(self.levels)
 
+        if allkinds is None:
+            allkinds = [[None] * len(segs) for segs in allsegs]
+
         # Check lengths of levels and allsegs.
         if self.filled:
-            if len(self.allsegs) != len(self.levels) - 1:
+            if len(allsegs) != len(self.levels) - 1:
                 raise ValueError('must be one less number of segments as '
                                  'levels')
         else:
-            if len(self.allsegs) != len(self.levels):
+            if len(allsegs) != len(self.levels):
                 raise ValueError('must be same number of segments as levels')
 
         # Check length of allkinds.
-        if (self.allkinds is not None and
-                len(self.allkinds) != len(self.allsegs)):
+        if len(allkinds) != len(allsegs):
             raise ValueError('allkinds has different length to allsegs')
 
         # Determine x, y bounds and update axes data limits.
-        flatseglist = [s for seg in self.allsegs for s in seg]
+        flatseglist = [s for seg in allsegs for s in seg]
         points = np.concatenate(flatseglist, axis=0)
         self._mins = points.min(axis=0)
         self._maxs = points.max(axis=0)
 
+        # Each entry in (allsegs, allkinds) is a list of (segs, kinds) which
+        # specifies a list of Paths: segs is a list of (N, 2) arrays of xy
+        # coordinates, kinds is a list of arrays of corresponding pathcodes.
+        # However, kinds can also be None; in which case all paths in that list
+        # are codeless (this case is normalized above).
+        self._allpaths = [[*map(mpath.Path, segs, kinds)]
+                          for segs, kinds in zip(allsegs, allkinds)]
+
         return kwargs
 
-    def _get_allsegs_and_allkinds(self):
-        """Compute ``allsegs`` and ``allkinds`` using C extension."""
-        allsegs = []
-        allkinds = []
+    def _get_allpaths(self):
+        """Compute ``allpaths`` using C extension."""
+        if self._allpaths is not None:
+            return self._allpaths
+        allpaths = []
         if self.filled:
             lowers, uppers = self._get_lowers_and_uppers()
             for level, level_upper in zip(lowers, uppers):
                 vertices, kinds = \
                     self._contour_generator.create_filled_contour(
                         level, level_upper)
-                allsegs.append(vertices)
-                allkinds.append(kinds)
+                allpaths.append([*map(mpath.Path, vertices, kinds)])
         else:
             for level in self.levels:
                 vertices, kinds = self._contour_generator.create_contour(level)
-                allsegs.append(vertices)
-                allkinds.append(kinds)
-        return allsegs, allkinds
+                allpaths.append([*map(mpath.Path, vertices, kinds)])
+        return allpaths
 
     def _get_lowers_and_uppers(self):
         """
@@ -1052,7 +1057,6 @@ def changed(self):
         self.norm.autoscale_None(self.levels)
         tcolors = [(tuple(rgba),)
                    for rgba in self.to_rgba(self.cvalues, alpha=self.alpha)]
-        self.tcolors = tcolors
         hatches = self.hatches * len(tcolors)
         for color, hatch, collection in zip(tcolors, hatches,
                                             self.collections):
diff --git a/lib/matplotlib/tests/test_contour.py b/lib/matplotlib/tests/test_contour.py
@@ -365,7 +365,7 @@ def test_contour_linewidth(
         fig, ax = plt.subplots()
         X = np.arange(4*3).reshape(4, 3)
         cs = ax.contour(X, linewidths=call_linewidths)
-        assert cs.tlinewidths[0][0] == expected
+        assert cs.collections[0].get_linewidths()[0] == expected
 
 
 @pytest.mark.backend("pdf")
