From e487b1c0d91f01e51c3203666b1a5e19d7c43920 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Fri, 23 Jul 2021 08:57:10 +0200
Subject: [PATCH 01/22] Add user supplied transforms and join/cap styles

Improvement was done in instantiating new instance
utilizing deep copy should preserve immutability of
MarkerStyle members (e.g. Path, or Transform).
---
 lib/matplotlib/markers.py | 50 ++++++++++++++++++++++++---------------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 8fbbb71818a4..644ab2a1aba7 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -127,6 +127,7 @@
 .. |m36| image:: /_static/markers/m36.png
 .. |m37| image:: /_static/markers/m37.png
 """
+import copy
 
 from collections.abc import Sized
 import inspect
@@ -221,7 +222,8 @@ class MarkerStyle:
 
     _unset = object()  # For deprecation of MarkerStyle(<noargs>).
 
-    def __init__(self, marker=_unset, fillstyle=None):
+    def __init__(self, marker=_unset, fillstyle=None,
+                 transform=None, capstyle=None, joinstyle=None):
         """
         Parameters
         ----------
@@ -236,6 +238,9 @@ def __init__(self, marker=_unset, fillstyle=None):
             One of 'full', 'left', 'right', 'bottom', 'top', 'none'.
         """
         self._marker_function = None
+        self._user_transform = transform
+        self._user_capstyle = capstyle
+        self._user_joinstyle = joinstyle
         self._set_fillstyle(fillstyle)
         # Remove _unset and signature rewriting after deprecation elapses.
         if marker is self._unset:
@@ -265,7 +270,7 @@ def _recache(self):
         self._alt_transform = None
         self._snap_threshold = None
         self._joinstyle = JoinStyle.round
-        self._capstyle = CapStyle.butt
+        self._capstyle = self._user_capstyle or CapStyle.butt
         # Initial guess: Assume the marker is filled unless the fillstyle is
         # set to 'none'. The marker function will override this for unfilled
         # markers.
@@ -342,7 +347,8 @@ def _set_marker(self, marker):
             self._marker_function = getattr(
                 self, '_set_' + self.markers[marker])
         elif isinstance(marker, MarkerStyle):
-            self.__dict__.update(marker.__dict__)
+            self.__dict__ = copy.deepcopy(marker.__dict__)
+
         else:
             try:
                 Path(marker)
@@ -369,7 +375,10 @@ def get_transform(self):
         Return the transform to be applied to the `.Path` from
         `MarkerStyle.get_path()`.
         """
-        return self._transform.frozen()
+        if self._user_transform is not None:
+            return (self._transform + self._user_transform).frozen()
+        else:
+            return self._transform.frozen()
 
     def get_alt_path(self):
         """
@@ -385,7 +394,10 @@ def get_alt_transform(self):
         Return the transform to be applied to the `.Path` from
         `MarkerStyle.get_alt_path()`.
         """
-        return self._alt_transform.frozen()
+        if self._user_transform is not None:
+            return (self._alt_transform + self._user_transform).frozen()
+        else:
+            return self._alt_transform.frozen()
 
     def get_snap_threshold(self):
         return self._snap_threshold
@@ -413,14 +425,14 @@ def _set_tuple_marker(self):
         symstyle = marker[1]
         if symstyle == 0:
             self._path = Path.unit_regular_polygon(numsides)
-            self._joinstyle = JoinStyle.miter
+            self._joinstyle = self._user_joinstyle or JoinStyle.miter
         elif symstyle == 1:
             self._path = Path.unit_regular_star(numsides)
-            self._joinstyle = JoinStyle.bevel
+            self._joinstyle = self._user_joinstyle or JoinStyle.bevel
         elif symstyle == 2:
             self._path = Path.unit_regular_asterisk(numsides)
             self._filled = False
-            self._joinstyle = JoinStyle.bevel
+            self._joinstyle = self._user_joinstyle or JoinStyle.bevel
         else:
             raise ValueError(f"Unexpected tuple marker: {marker}")
         self._transform = Affine2D().scale(0.5).rotate_deg(rotation)
@@ -521,7 +533,7 @@ def _set_triangle(self, rot, skip):
 
             self._alt_transform = self._transform
 
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     def _set_triangle_up(self):
         return self._set_triangle(0.0, 0)
@@ -551,7 +563,7 @@ def _set_square(self):
             self._transform.rotate_deg(rotate)
             self._alt_transform = self._transform
 
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     def _set_diamond(self):
         self._transform = Affine2D().translate(-0.5, -0.5).rotate_deg(45)
@@ -565,7 +577,7 @@ def _set_diamond(self):
             rotate = {'right': 0, 'top': 90, 'left': 180, 'bottom': 270}[fs]
             self._transform.rotate_deg(rotate)
             self._alt_transform = self._transform
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     def _set_thin_diamond(self):
         self._set_diamond()
@@ -592,7 +604,7 @@ def _set_pentagon(self):
             }[self.get_fillstyle()]
             self._alt_transform = self._transform
 
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     def _set_star(self):
         self._transform = Affine2D().scale(0.5)
@@ -614,7 +626,7 @@ def _set_star(self):
             }[self.get_fillstyle()]
             self._alt_transform = self._transform
 
-        self._joinstyle = JoinStyle.bevel
+        self._joinstyle = self._user_joinstyle or JoinStyle.bevel
 
     def _set_hexagon1(self):
         self._transform = Affine2D().scale(0.5)
@@ -638,7 +650,7 @@ def _set_hexagon1(self):
             }[self.get_fillstyle()]
             self._alt_transform = self._transform
 
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     def _set_hexagon2(self):
         self._transform = Affine2D().scale(0.5).rotate_deg(30)
@@ -664,7 +676,7 @@ def _set_hexagon2(self):
             }[self.get_fillstyle()]
             self._alt_transform = self._transform
 
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     def _set_octagon(self):
         self._transform = Affine2D().scale(0.5)
@@ -685,7 +697,7 @@ def _set_octagon(self):
                 {'left': 0, 'bottom': 90, 'right': 180, 'top': 270}[fs])
             self._alt_transform = self._transform.frozen().rotate_deg(180.0)
 
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     _line_marker_path = Path([[0.0, -1.0], [0.0, 1.0]])
 
@@ -759,7 +771,7 @@ def _set_caretdown(self):
         self._snap_threshold = 3.0
         self._filled = False
         self._path = self._caret_path
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
 
     def _set_caretup(self):
         self._set_caretdown()
@@ -825,7 +837,7 @@ def _set_x(self):
     def _set_plus_filled(self):
         self._transform = Affine2D()
         self._snap_threshold = 5.0
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
         if not self._half_fill():
             self._path = self._plus_filled_path
         else:
@@ -849,7 +861,7 @@ def _set_plus_filled(self):
     def _set_x_filled(self):
         self._transform = Affine2D()
         self._snap_threshold = 5.0
-        self._joinstyle = JoinStyle.miter
+        self._joinstyle = self._user_joinstyle or JoinStyle.miter
         if not self._half_fill():
             self._path = self._x_filled_path
         else:

From 37859ea33869d86c4e57aaa3512a705092e774be Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Thu, 26 Aug 2021 20:40:53 +0200
Subject: [PATCH 02/22] Avoid reinstanting MarkerStyle in lines.py

---
 lib/matplotlib/lines.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/matplotlib/lines.py b/lib/matplotlib/lines.py
index ea3b98b63208..f1efd125a4ed 100644
--- a/lib/matplotlib/lines.py
+++ b/lib/matplotlib/lines.py
@@ -370,7 +370,10 @@ def __init__(self, xdata, ydata,
         self.set_color(color)
         if marker is None:
             marker = 'none'  # Default.
-        self._marker = MarkerStyle(marker, fillstyle)
+        if not isinstance(marker, MarkerStyle):
+            self._marker = MarkerStyle(marker, fillstyle)
+        else:
+            self._marker = marker
 
         self._markevery = None
         self._markersize = None

From 81536320d4a702db9376782ee7ac6b5a6f43971c Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Sun, 5 Sep 2021 23:30:26 +0200
Subject: [PATCH 03/22] Update  dosctring.

---
 lib/matplotlib/markers.py | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 644ab2a1aba7..b4413bbe3ba0 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -236,6 +236,18 @@ def __init__(self, marker=_unset, fillstyle=None,
 
         fillstyle : str, default: :rc:`markers.fillstyle`
             One of 'full', 'left', 'right', 'bottom', 'top', 'none'.
+        
+        transform : Affine2D, default: None
+            User supplied transformation that will be combined with the
+            native transformation of selected marker.
+
+        capstyle : CapStyle, default: None
+            User supplied cap style that will override the default cap
+            style of selected marker.
+
+        joinstyle : JoinStyle, default: None
+            User supplied join style that will override the default cap
+            style of selected marker.
         """
         self._marker_function = None
         self._user_transform = transform

From 4469006fb4b8720876b938023561233dd9588993 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Mon, 6 Sep 2021 22:56:14 +0200
Subject: [PATCH 04/22] Add marker.transformed + test

---
 lib/matplotlib/markers.py           | 51 +++++++++++++++++++++++++++--
 lib/matplotlib/tests/test_marker.py | 11 +++++++
 2 files changed, 59 insertions(+), 3 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index b4413bbe3ba0..5652382c945a 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -236,7 +236,7 @@ def __init__(self, marker=_unset, fillstyle=None,
 
         fillstyle : str, default: :rc:`markers.fillstyle`
             One of 'full', 'left', 'right', 'bottom', 'top', 'none'.
-        
+
         transform : Affine2D, default: None
             User supplied transformation that will be combined with the
             native transformation of selected marker.
@@ -319,10 +319,10 @@ def _set_fillstyle(self, fillstyle):
         self._recache()
 
     def get_joinstyle(self):
-        return self._joinstyle
+        return self._user_joinstyle or self._joinstyle
 
     def get_capstyle(self):
-        return self._capstyle
+        return self._user_capstyle or self._capstyle
 
     def get_marker(self):
         return self._marker
@@ -414,6 +414,51 @@ def get_alt_transform(self):
     def get_snap_threshold(self):
         return self._snap_threshold
 
+    def get_user_transform(self):
+        """Return user supplied part of marker transform."""
+        if self._user_transform is not None:
+            return self._user_transform.frozen()
+
+    def transformed(self, transform:Affine2D):
+        """
+        Return new marker with combined transformation.
+
+        Parameters
+        ----------
+        transform : Affine2D, default: None
+            - transform will be combined with current user supplied transform.
+        """
+        new_marker = MarkerStyle(self)
+        if new_marker._user_transform is not None:
+            new_marker._user_transform += transform
+        else:
+            new_marker._user_transform = transform
+        return new_marker
+
+    def rotated(self, deg=None, rad=None):
+        """
+        Return new marker rotated by specified angle.
+
+        Parameters
+        ----------
+        deg : float, default: None
+
+        rad : float, default: None
+        """
+        if not ((deg is None) ^ (rad is None)):
+            raise Exception("Only one of deg or rad shall be used.")
+        
+        _transform = self._user_transform or Affine2D()
+
+        if deg is not None: 
+            _transform = _transform.rotate_deg(deg)
+        
+        if rad is not None:
+            _transform = _transform.rotate(rad)
+
+        new_marker = MarkerStyle(self)
+        new_marker._user_transform = _transform
+
     def _set_nothing(self):
         self._filled = False
 
diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
index 75681b0e1a9b..11c9564a9218 100644
--- a/lib/matplotlib/tests/test_marker.py
+++ b/lib/matplotlib/tests/test_marker.py
@@ -4,6 +4,7 @@
 from matplotlib._api.deprecation import MatplotlibDeprecationWarning
 from matplotlib.path import Path
 from matplotlib.testing.decorators import check_figures_equal
+from matplotlib.transforms import Affine2D
 
 import pytest
 
@@ -204,3 +205,13 @@ def test_marker_clipping(fig_ref, fig_test):
     ax_test.set(xlim=(-0.5, ncol), ylim=(-0.5, 2 * nrow))
     ax_ref.axis('off')
     ax_test.axis('off')
+
+@pytest.mark.parametrize("marker,transform,expected", [
+    (markers.MarkerStyle("o"), Affine2D().translate(1,1), Affine2D().translate(1,1)),
+    (markers.MarkerStyle("o", transform=Affine2D().translate(1,1)), Affine2D().translate(1,1), Affine2D().translate(2,2)),
+])
+def test_marker_transformed(marker, transform, expected):
+    new_marker = marker.transformed(transform)
+    assert new_marker is not marker
+    assert new_marker.get_user_transform() == expected
+    assert marker.get_user_transform() is not new_marker.get_user_transform()
\ No newline at end of file

From 4ea2b913da2932e08a3d8eea4ad0ff63290d4306 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Fri, 10 Sep 2021 23:10:54 +0200
Subject: [PATCH 05/22] Add affine transform primitives to markers

Added, translated, scaled, and rotated methods with test.
---
 lib/matplotlib/markers.py           | 61 ++++++++++++++++++++++++-----
 lib/matplotlib/tests/test_marker.py | 41 +++++++++++++++++--
 2 files changed, 90 insertions(+), 12 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 5652382c945a..90532104f8a9 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -419,7 +419,7 @@ def get_user_transform(self):
         if self._user_transform is not None:
             return self._user_transform.frozen()
 
-    def transformed(self, transform:Affine2D):
+    def transformed(self, transform: Affine2D):
         """
         Return new marker with combined transformation.
 
@@ -442,22 +442,65 @@ def rotated(self, deg=None, rad=None):
         Parameters
         ----------
         deg : float, default: None
+            - use this parameter to specify rotation angle in degrees.
 
         rad : float, default: None
+            - use this parameter to specify rotation angle in radians.
+
+        Note: you must specify exactly one of deg or rad.
         """
         if not ((deg is None) ^ (rad is None)):
-            raise Exception("Only one of deg or rad shall be used.")
-        
-        _transform = self._user_transform or Affine2D()
+            raise ValueError("Exactly one of deg or rad shall be used.")
+
+        new_marker = MarkerStyle(self)
+        if new_marker._user_transform is None:
+            new_marker._user_transform = Affine2D()
 
-        if deg is not None: 
-            _transform = _transform.rotate_deg(deg)
-        
+        if deg is not None:
+            new_marker._user_transform.rotate_deg(deg)
         if rad is not None:
-            _transform = _transform.rotate(rad)
+            new_marker._user_transform.rotate(rad)
+
+        return new_marker
+
+    def scaled(self, sx, sy=None):
+        """
+        Return new marker scaled by specified scale factors.
+
+        If *sy* is None, the same scale is applied in both the *x*- and
+        *y*-directions.
+
+        Parameters
+        ----------
+        sx : float
+        - *x*-direction scaling factor.
+
+        sy : float, default: None
+        - *y*-direction scaling factor.
+        """
+        if sy is None:
+            sy = sx
+
+        new_marker = MarkerStyle(self)
+        _transform = new_marker._user_transform or Affine2D()
+        new_marker._user_transform = _transform.scale(sx, sy)
+        return new_marker
+
+    def translated(self, tx, ty):
+        """
+        Return new marker translated by tx and ty.
 
+        Parameters
+        ----------
+        tx : float
+
+        ty : float
+
+        """
         new_marker = MarkerStyle(self)
-        new_marker._user_transform = _transform
+        _transform = new_marker._user_transform or Affine2D()
+        new_marker._user_transform = _transform.translate(tx, ty)
+        return new_marker
 
     def _set_nothing(self):
         self._filled = False
diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
index 11c9564a9218..db2aaa768e8f 100644
--- a/lib/matplotlib/tests/test_marker.py
+++ b/lib/matplotlib/tests/test_marker.py
@@ -206,12 +206,47 @@ def test_marker_clipping(fig_ref, fig_test):
     ax_ref.axis('off')
     ax_test.axis('off')
 
+
 @pytest.mark.parametrize("marker,transform,expected", [
-    (markers.MarkerStyle("o"), Affine2D().translate(1,1), Affine2D().translate(1,1)),
-    (markers.MarkerStyle("o", transform=Affine2D().translate(1,1)), Affine2D().translate(1,1), Affine2D().translate(2,2)),
+    (markers.MarkerStyle("o"), Affine2D().translate(1, 1),
+        Affine2D().translate(1, 1)),
+    (markers.MarkerStyle("o", transform=Affine2D().translate(1, 1)),
+        Affine2D().translate(1, 1), Affine2D().translate(2, 2)),
+    # (markers.MarkerStyle("$|||$", transform=Affine2D().translate(1, 1)),
+    #  Affine2D().translate(1, 1), Affine2D().translate(2, 2)),
+    (markers.MarkerStyle(
+        markers.TICKLEFT, transform=Affine2D().translate(1, 1)),
+        Affine2D().translate(1, 1), Affine2D().translate(2, 2)),
 ])
 def test_marker_transformed(marker, transform, expected):
     new_marker = marker.transformed(transform)
     assert new_marker is not marker
     assert new_marker.get_user_transform() == expected
-    assert marker.get_user_transform() is not new_marker.get_user_transform()
\ No newline at end of file
+    assert marker._user_transform is not new_marker._user_transform
+
+
+def test_marker_rotated_invalid():
+    marker = markers.MarkerStyle("o")
+    with pytest.raises(ValueError):
+        new_marker = marker.rotated()
+        new_marker = marker.rotated(deg=10, rad=10)
+
+
+@pytest.mark.parametrize("marker,deg,rad,expected", [
+    (markers.MarkerStyle("o"), 10, None, Affine2D().rotate_deg(10)),
+    (markers.MarkerStyle("o"), None, 0.01, Affine2D().rotate(0.01)),
+    (markers.MarkerStyle("o", transform=Affine2D().translate(1, 1)),
+        10, None, Affine2D().translate(1, 1).rotate_deg(10)),
+    (markers.MarkerStyle("o", transform=Affine2D().translate(1, 1)),
+        None, 0.01, Affine2D().translate(1, 1).rotate(0.01)),
+    # (markers.MarkerStyle("$|||$", transform=Affine2D().translate(1, 1)),
+    #   10, None, Affine2D().translate(1, 1).rotate_deg(10)),
+    (markers.MarkerStyle(
+        markers.TICKLEFT, transform=Affine2D().translate(1, 1)),
+        10, None, Affine2D().translate(1, 1).rotate_deg(10)),
+])
+def test_marker_rotated_deg(marker, deg, rad, expected):
+    new_marker = marker.rotated(deg=deg, rad=rad)
+    assert new_marker is not marker
+    assert new_marker.get_user_transform() == expected
+    assert marker._user_transform is not new_marker._user_transform

From 7f6d1bece34f6dbbb8ab917e828acc2edda34425 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Sat, 11 Sep 2021 20:20:54 +0200
Subject: [PATCH 06/22] Tweaking docstrings in MarkerStyle.

---
 lib/matplotlib/markers.py | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 90532104f8a9..fc639fd6fbd8 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -426,7 +426,7 @@ def transformed(self, transform: Affine2D):
         Parameters
         ----------
         transform : Affine2D, default: None
-            - transform will be combined with current user supplied transform.
+            Transform will be combined with current user supplied transform.
         """
         new_marker = MarkerStyle(self)
         if new_marker._user_transform is not None:
@@ -442,12 +442,12 @@ def rotated(self, deg=None, rad=None):
         Parameters
         ----------
         deg : float, default: None
-            - use this parameter to specify rotation angle in degrees.
+            Use this parameter to specify rotation angle in degrees.
 
         rad : float, default: None
-            - use this parameter to specify rotation angle in radians.
+            Use this parameter to specify rotation angle in radians.
 
-        Note: you must specify exactly one of deg or rad.
+        .. note:: You must specify exactly one of deg or rad.
         """
         if not ((deg is None) ^ (rad is None)):
             raise ValueError("Exactly one of deg or rad shall be used.")
@@ -473,10 +473,9 @@ def scaled(self, sx, sy=None):
         Parameters
         ----------
         sx : float
-        - *x*-direction scaling factor.
-
+            *X*-direction scaling factor.
         sy : float, default: None
-        - *y*-direction scaling factor.
+            *Y*-direction scaling factor.
         """
         if sy is None:
             sy = sx
@@ -493,9 +492,9 @@ def translated(self, tx, ty):
         Parameters
         ----------
         tx : float
-
+            Coordinate for translation in *x*-direction.
         ty : float
-
+            Coordinate for translation in *y*-direction.
         """
         new_marker = MarkerStyle(self)
         _transform = new_marker._user_transform or Affine2D()

From 2729fe43217ea810c33131eb640aac8c5c45abd3 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Sun, 12 Sep 2021 17:05:03 +0200
Subject: [PATCH 07/22] Update MarkerStyle module documentation

---
 lib/matplotlib/markers.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index fc639fd6fbd8..b380e1203484 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -82,6 +82,13 @@
     plt.plot([1, 2, 3], marker=11)
     plt.plot([1, 2, 3], marker=matplotlib.markers.CARETDOWNBASE)
 
+Markers have some reasonable default settings for join and cap styles.
+However, those can be overriden when creating a new instance of MarkerStyle.
+Furthermore, the marker shape can be modified by supplying
+`~matplotlib .transforms.Transform` during creation.
+Some markers are created as internally rotated shapes (e.g. triangles).
+For such cases, both internal and user supplied transforms are combined.
+
 Examples showing the use of markers:
 
 * :doc:`/gallery/lines_bars_and_markers/marker_reference`

From 435799533a9a2a741d0b04aad23b64730263ebd7 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Sun, 12 Sep 2021 17:05:38 +0200
Subject: [PATCH 08/22] Update marker Reference documentation

---
 .../marker_reference.py                       | 97 +++++++++++++++++++
 1 file changed, 97 insertions(+)

diff --git a/examples/lines_bars_and_markers/marker_reference.py b/examples/lines_bars_and_markers/marker_reference.py
index 98af2519124c..d1d675c5c268 100644
--- a/examples/lines_bars_and_markers/marker_reference.py
+++ b/examples/lines_bars_and_markers/marker_reference.py
@@ -19,8 +19,10 @@
 .. redirect-from:: /gallery/shapes_and_collections/marker_path
 """
 
+from matplotlib.markers import MarkerStyle
 import matplotlib.pyplot as plt
 from matplotlib.lines import Line2D
+from matplotlib.transforms import Affine2D
 
 
 text_style = dict(horizontalalignment='right', verticalalignment='center',
@@ -159,3 +161,98 @@ def split_list(a_list):
 format_axes(ax)
 
 plt.show()
+
+###############################################################################
+# Advanced marker modifications with transform
+# ============================================
+#
+# All markers can be modified by a user transform in MarkerStyle constructor.
+# Supplied transform is combined with the default transforms needed for
+# selected marker shape (e.g. caret up, caret down). Following example shows
+# how user supplied rotation applies to several marker shapes.
+
+common_style = {k: v for k, v in filled_marker_style.items() if v != 'marker'}
+angles = [0, 10, 20, 30, 45, 60, 90]
+
+fig, ax = plt.subplots()
+fig.suptitle('Rotated markers', fontsize=14)
+
+ax.text(-0.5, 0, 'Filled marker', **text_style)
+for x, theta in enumerate(angles):
+    t = Affine2D().rotate_deg(theta)
+    ax.plot(x, 0, marker=MarkerStyle('o', 'left', t), **common_style)
+
+ax.text(-0.5, 1, 'Un-filled marker', **text_style)
+for x, theta in enumerate(angles):
+    t = Affine2D().rotate_deg(theta)
+    ax.plot(x, 1, marker=MarkerStyle('1', 'left', t), **common_style)
+
+ax.text(-0.5, 2, 'Equation marker', **text_style)
+for x, theta in enumerate(angles):
+    t = Affine2D().rotate_deg(theta)
+    eq = r'$\frac{1}{x}$'
+    ax.plot(x, 2, marker=MarkerStyle(eq, 'left', t), **common_style)
+
+for x, theta in enumerate(angles):
+    ax.text(x, 2.5, f"{theta}°", horizontalalignment="center")
+format_axes(ax)
+
+plt.show()
+
+###############################################################################
+# Setting marker cap style and join style
+# =======================================
+#
+# All markers have predefined cap style and join style, but this can be
+# overriden during creation of MarkerStyle. Follwing example show how to
+# change the cap style and how different styles look.
+
+from matplotlib.markers import JoinStyle, CapStyle
+
+marker_inner = dict(markersize=35,
+                    markerfacecolor='tab:blue',
+                    markerfacecoloralt='lightsteelblue',
+                    markeredgecolor='brown',
+                    markeredgewidth=8,
+                    )
+
+marker_outer = dict(markersize=35,
+                    markerfacecolor='tab:blue',
+                    markerfacecoloralt='lightsteelblue',
+                    markeredgecolor='white',
+                    markeredgewidth=1,
+                    )
+
+fig, ax = plt.subplots()
+fig.suptitle('Marker CapStyle', fontsize=14)
+fig.subplots_adjust(left=0.1)
+
+for y, cap_style in enumerate([None, *CapStyle]):
+    ax.text(-0.5, y, cap_style.name, **text_style)
+    for x, theta in enumerate(angles):
+        t = Affine2D().rotate_deg(theta)
+        m = MarkerStyle('1', transform=t, capstyle=cap_style)
+        ax.plot(x, y, marker=m, **marker_inner)
+        ax.plot(x, y, marker=m, **marker_outer)
+        ax.text(x, len(CapStyle) - .5, f'{theta}°', ha='center')
+format_axes(ax)
+plt.show()
+
+###############################################################################
+# Follwing example show how to change the join style and how different styles
+# look.
+
+fig, ax = plt.subplots()
+fig.suptitle('Marker JoinStyle', fontsize=14)
+fig.subplots_adjust(left=0.05)
+
+for y, join_style in enumerate(JoinStyle):
+    ax.text(-0.5, y, join_style.name, **text_style)
+    for x, theta in enumerate(angles):
+        t = Affine2D().rotate_deg(theta)
+        m = MarkerStyle('*', transform=t, joinstyle=join_style)
+        ax.plot(x, y, marker=m, **marker_inner)
+        ax.text(x, len(JoinStyle) - .5, f'{theta}°', ha='center')
+format_axes(ax)
+
+plt.show()

From b1bbdff12758e8e0a30841ba075cdd6c9c2485c6 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Sun, 12 Sep 2021 17:06:03 +0200
Subject: [PATCH 09/22] Add whats new for MarkerStyle features

---
 .../next_whats_new/extending_MarkerStyle.rst  | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 doc/users/next_whats_new/extending_MarkerStyle.rst

diff --git a/doc/users/next_whats_new/extending_MarkerStyle.rst b/doc/users/next_whats_new/extending_MarkerStyle.rst
new file mode 100644
index 000000000000..06479a7badf8
--- /dev/null
+++ b/doc/users/next_whats_new/extending_MarkerStyle.rst
@@ -0,0 +1,19 @@
+New customization of MarkerStyle
+--------------------------------
+
+New MarkerStyle parameters allow control of join style and cap style. 
+The appearance of individual markers can be further controlled by 
+transform supplied during creation.
+
+.. plot::
+    :include-source:
+    import matplotlib.pyplot as plt
+    from matplotlib.markers import MarkerStyle
+    from matplotlib.transforms import Affine2D
+    fig, ax = plt.subplots(figsize=(6, 1))
+    fig.suptitle('New markers', fontsize=14)
+    for col, (size, rot) in enumerate(zip([2, 5, 10], [0, 45, 90])):
+        t = Affine2D().rotate_deg(rot).scale(size)
+        ax.plot(col, 0, marker=MarkerStyle("*", transform=t))
+    ax.axis("off")
+    ax.set_xlim(-0.1, 2.4)

From 9ac3ad2f6e5a14ab12a1dabf975ba71fa466f42f Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Sun, 12 Sep 2021 19:27:36 +0200
Subject: [PATCH 10/22] Add new example with advanced MarkerStyle mapping

---
 .../multivariate_marker_plot.py               | 45 +++++++++++++++++++
 lib/matplotlib/markers.py                     |  2 +-
 2 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 examples/lines_bars_and_markers/multivariate_marker_plot.py

diff --git a/examples/lines_bars_and_markers/multivariate_marker_plot.py b/examples/lines_bars_and_markers/multivariate_marker_plot.py
new file mode 100644
index 000000000000..274a1113fbc1
--- /dev/null
+++ b/examples/lines_bars_and_markers/multivariate_marker_plot.py
@@ -0,0 +1,45 @@
+"""
+==============================================
+Mapping marker properties to multivariate data
+==============================================
+
+This example shows how to use different properties of markers to plot
+multivariate datasets. Following example shows an illustrative case of
+plotting success of baseball throw as an smiley face with size mapped to
+the skill of thrower, rotation mapped to the take-off angle, and thrust
+to the color of the marker.
+"""
+
+import numpy as np
+import matplotlib.pyplot as plt
+from matplotlib.markers import MarkerStyle
+from matplotlib.transforms import Affine2D
+from matplotlib.textpath import TextPath
+from matplotlib.colors import Normalize
+
+SUCCESS_SYMBOLS = [
+    TextPath((0,0), "☹"), 
+    TextPath((0,0), "😒"), 
+    TextPath((0,0), "☺"), 
+]
+
+N = 25
+np.random.seed(42)
+skills = np.random.uniform(5, 80, size=N) * 0.1 + 5
+takeoff_angles = np.random.normal(0, 90, N)
+thrusts = np.random.uniform(size=N)
+successfull = np.random.randint(0, 3, size=N)
+positions = np.random.normal(size=(N, 2)) * 5
+data = zip(skills, takeoff_angles, thrusts, successfull, positions)
+
+cmap = plt.cm.get_cmap("plasma")
+fig, ax = plt.subplots()
+fig.suptitle("Throwing success", size=14)
+for skill, takeoff, thrust, mood, pos in data:
+    t = Affine2D().scale(skill).rotate_deg(takeoff)
+    m = MarkerStyle(SUCCESS_SYMBOLS[mood], transform=t)
+    ax.plot(pos[0], pos[1], marker=m, color=cmap(thrust))
+fig.colorbar(plt.cm.ScalarMappable(norm=Normalize(0, 1), cmap=cmap),
+    ax=ax, label="Normalized Thrust [a.u.]")
+ax.set_xlabel("X position [m]")
+ax.set_ylabel("Y position [m]")
diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index b380e1203484..86b3492d8776 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -93,7 +93,7 @@
 
 * :doc:`/gallery/lines_bars_and_markers/marker_reference`
 * :doc:`/gallery/lines_bars_and_markers/scatter_star_poly`
-
+* :doc:`/gallery/lines_bars_and_markers/multivariate_marker_plot`
 
 .. |m00| image:: /_static/markers/m00.png
 .. |m01| image:: /_static/markers/m01.png

From 41808430ace77c5dfdbb815c1d2e26ad3c1e8181 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Sun, 12 Sep 2021 23:40:33 +0200
Subject: [PATCH 11/22] Fix errors discovered by CI

---
 doc/users/next_whats_new/extending_MarkerStyle.rst        | 3 ++-
 examples/lines_bars_and_markers/marker_reference.py       | 6 +++---
 .../lines_bars_and_markers/multivariate_marker_plot.py    | 8 ++++----
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/doc/users/next_whats_new/extending_MarkerStyle.rst b/doc/users/next_whats_new/extending_MarkerStyle.rst
index 06479a7badf8..fbe0fadd7f0c 100644
--- a/doc/users/next_whats_new/extending_MarkerStyle.rst
+++ b/doc/users/next_whats_new/extending_MarkerStyle.rst
@@ -6,7 +6,8 @@ The appearance of individual markers can be further controlled by
 transform supplied during creation.
 
 .. plot::
-    :include-source:
+    :include-source: true
+    
     import matplotlib.pyplot as plt
     from matplotlib.markers import MarkerStyle
     from matplotlib.transforms import Affine2D
diff --git a/examples/lines_bars_and_markers/marker_reference.py b/examples/lines_bars_and_markers/marker_reference.py
index d1d675c5c268..f82ec36035e6 100644
--- a/examples/lines_bars_and_markers/marker_reference.py
+++ b/examples/lines_bars_and_markers/marker_reference.py
@@ -171,7 +171,7 @@ def split_list(a_list):
 # selected marker shape (e.g. caret up, caret down). Following example shows
 # how user supplied rotation applies to several marker shapes.
 
-common_style = {k: v for k, v in filled_marker_style.items() if v != 'marker'}
+common_style = {k: v for k, v in filled_marker_style.items() if k != 'marker'}
 angles = [0, 10, 20, 30, 45, 60, 90]
 
 fig, ax = plt.subplots()
@@ -227,7 +227,7 @@ def split_list(a_list):
 fig.suptitle('Marker CapStyle', fontsize=14)
 fig.subplots_adjust(left=0.1)
 
-for y, cap_style in enumerate([None, *CapStyle]):
+for y, cap_style in enumerate(CapStyle):
     ax.text(-0.5, y, cap_style.name, **text_style)
     for x, theta in enumerate(angles):
         t = Affine2D().rotate_deg(theta)
@@ -240,7 +240,7 @@ def split_list(a_list):
 
 ###############################################################################
 # Follwing example show how to change the join style and how different styles
-# look.
+# looks like.
 
 fig, ax = plt.subplots()
 fig.suptitle('Marker JoinStyle', fontsize=14)
diff --git a/examples/lines_bars_and_markers/multivariate_marker_plot.py b/examples/lines_bars_and_markers/multivariate_marker_plot.py
index 274a1113fbc1..51d7d4bca30e 100644
--- a/examples/lines_bars_and_markers/multivariate_marker_plot.py
+++ b/examples/lines_bars_and_markers/multivariate_marker_plot.py
@@ -18,9 +18,9 @@
 from matplotlib.colors import Normalize
 
 SUCCESS_SYMBOLS = [
-    TextPath((0,0), "☹"), 
-    TextPath((0,0), "😒"), 
-    TextPath((0,0), "☺"), 
+    TextPath((0, 0), "☹"),
+    TextPath((0, 0), "😒"),
+    TextPath((0, 0), "☺"),
 ]
 
 N = 25
@@ -40,6 +40,6 @@
     m = MarkerStyle(SUCCESS_SYMBOLS[mood], transform=t)
     ax.plot(pos[0], pos[1], marker=m, color=cmap(thrust))
 fig.colorbar(plt.cm.ScalarMappable(norm=Normalize(0, 1), cmap=cmap),
-    ax=ax, label="Normalized Thrust [a.u.]")
+             ax=ax, label="Normalized Thrust [a.u.]")
 ax.set_xlabel("X position [m]")
 ax.set_ylabel("Y position [m]")

From 905eba488f9d2f0db420bd710b4fdc465397a2d8 Mon Sep 17 00:00:00 2001
From: Jakub Klus <48711526+deep-jkl@users.noreply.github.com>
Date: Mon, 13 Sep 2021 08:07:33 +0200
Subject: [PATCH 12/22] Fix typo in markers api documentation.

Apply suggestion from @timhoffm, update lib/matplotlib/markers.py

Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
---
 lib/matplotlib/markers.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 86b3492d8776..ad06879532f6 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -85,7 +85,7 @@
 Markers have some reasonable default settings for join and cap styles.
 However, those can be overriden when creating a new instance of MarkerStyle.
 Furthermore, the marker shape can be modified by supplying
-`~matplotlib .transforms.Transform` during creation.
+`~matplotlib.transforms.Transform` during creation.
 Some markers are created as internally rotated shapes (e.g. triangles).
 For such cases, both internal and user supplied transforms are combined.
 

From 3fc6140998d3a8cf130d53e161c0b2b4ff852a18 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Wed, 15 Sep 2021 00:32:03 +0200
Subject: [PATCH 13/22] Improve test for invalid rotated inputs

---
 lib/matplotlib/markers.py           | 2 +-
 lib/matplotlib/tests/test_marker.py | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index ad06879532f6..2a51d8fa5e9a 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -456,7 +456,7 @@ def rotated(self, deg=None, rad=None):
 
         .. note:: You must specify exactly one of deg or rad.
         """
-        if not ((deg is None) ^ (rad is None)):
+        if not (deg is None) ^ (rad is None):
             raise ValueError("Exactly one of deg or rad shall be used.")
 
         new_marker = MarkerStyle(self)
diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
index db2aaa768e8f..e2b18354f34a 100644
--- a/lib/matplotlib/tests/test_marker.py
+++ b/lib/matplotlib/tests/test_marker.py
@@ -229,6 +229,7 @@ def test_marker_rotated_invalid():
     marker = markers.MarkerStyle("o")
     with pytest.raises(ValueError):
         new_marker = marker.rotated()
+    with pytest.raises(ValueError):    
         new_marker = marker.rotated(deg=10, rad=10)
 
 

From 04a3e7046b0ae8c54f3fbd70b35d975005731a03 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Wed, 15 Sep 2021 00:39:35 +0200
Subject: [PATCH 14/22] Add tests for MarkerStyle scaled and translated

---
 lib/matplotlib/tests/test_marker.py | 38 +++++++++++++++++++++++++++--
 1 file changed, 36 insertions(+), 2 deletions(-)

diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
index e2b18354f34a..7925f22f54f7 100644
--- a/lib/matplotlib/tests/test_marker.py
+++ b/lib/matplotlib/tests/test_marker.py
@@ -229,7 +229,7 @@ def test_marker_rotated_invalid():
     marker = markers.MarkerStyle("o")
     with pytest.raises(ValueError):
         new_marker = marker.rotated()
-    with pytest.raises(ValueError):    
+    with pytest.raises(ValueError):
         new_marker = marker.rotated(deg=10, rad=10)
 
 
@@ -246,8 +246,42 @@ def test_marker_rotated_invalid():
         markers.TICKLEFT, transform=Affine2D().translate(1, 1)),
         10, None, Affine2D().translate(1, 1).rotate_deg(10)),
 ])
-def test_marker_rotated_deg(marker, deg, rad, expected):
+def test_marker_rotated(marker, deg, rad, expected):
     new_marker = marker.rotated(deg=deg, rad=rad)
     assert new_marker is not marker
     assert new_marker.get_user_transform() == expected
     assert marker._user_transform is not new_marker._user_transform
+
+
+def test_marker_translated():
+    marker = markers.MarkerStyle("1")
+    new_marker = marker.translated(1, 1)
+    assert new_marker is not marker
+    assert new_marker.get_user_transform() == Affine2D().translate(1, 1)
+    assert marker._user_transform is not new_marker._user_transform
+
+    marker = markers.MarkerStyle("1", transform=Affine2D().translate(1, 1))
+    new_marker = marker.translated(1, 1)
+    assert new_marker is not marker
+    assert new_marker.get_user_transform() == Affine2D().translate(2, 2)
+    assert marker._user_transform is not new_marker._user_transform
+
+
+def test_marker_scaled():
+    marker = markers.MarkerStyle("1")
+    new_marker = marker.scaled(2)
+    assert new_marker is not marker
+    assert new_marker.get_user_transform() == Affine2D().scale(2)
+    assert marker._user_transform is not new_marker._user_transform
+
+    new_marker = marker.scaled(2, 3)
+    assert new_marker is not marker
+    assert new_marker.get_user_transform() == Affine2D().scale(2, 3)
+    assert marker._user_transform is not new_marker._user_transform
+
+    marker = markers.MarkerStyle("1", transform=Affine2D().translate(1, 1))
+    new_marker = marker.scaled(2)
+    assert new_marker is not marker
+    expected = Affine2D().translate(1, 1).scale(2)
+    assert new_marker.get_user_transform() == expected
+    assert marker._user_transform is not new_marker._user_transform

From af6b89ad58025d24fe73d8292a8c5e08f4d330bd Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Wed, 15 Sep 2021 22:09:27 +0200
Subject: [PATCH 15/22] Add function for optimized None+transform

---
 lib/matplotlib/markers.py | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 2a51d8fa5e9a..e8fafd909e19 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -154,6 +154,14 @@
 _empty_path = Path(np.empty((0, 2)))
 
 
+def _fast_transform_combine(t1, t2):
+    """Combine two transformations where the second one can be None."""
+    if t2 is None:
+        return t1.frozen()
+    else:
+        return (t1 + t2).frozen()
+
+
 class MarkerStyle:
     """
     A class representing marker types.
@@ -394,10 +402,7 @@ def get_transform(self):
         Return the transform to be applied to the `.Path` from
         `MarkerStyle.get_path()`.
         """
-        if self._user_transform is not None:
-            return (self._transform + self._user_transform).frozen()
-        else:
-            return self._transform.frozen()
+        return _fast_transform_combine(self._transform, self._user_transform)
 
     def get_alt_path(self):
         """
@@ -413,10 +418,8 @@ def get_alt_transform(self):
         Return the transform to be applied to the `.Path` from
         `MarkerStyle.get_alt_path()`.
         """
-        if self._user_transform is not None:
-            return (self._alt_transform + self._user_transform).frozen()
-        else:
-            return self._alt_transform.frozen()
+        return _fast_transform_combine(self._alt_transform,
+                                       self._user_transform)
 
     def get_snap_threshold(self):
         return self._snap_threshold

From c01e8f1b5e1786b7be1159e92833496712ac7e89 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Wed, 15 Sep 2021 22:11:05 +0200
Subject: [PATCH 16/22] Remove ambiguous translated primitive for MarkerStyle

---
 lib/matplotlib/markers.py           | 16 ----------------
 lib/matplotlib/tests/test_marker.py | 14 --------------
 2 files changed, 30 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index e8fafd909e19..6a839d040495 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -495,22 +495,6 @@ def scaled(self, sx, sy=None):
         new_marker._user_transform = _transform.scale(sx, sy)
         return new_marker
 
-    def translated(self, tx, ty):
-        """
-        Return new marker translated by tx and ty.
-
-        Parameters
-        ----------
-        tx : float
-            Coordinate for translation in *x*-direction.
-        ty : float
-            Coordinate for translation in *y*-direction.
-        """
-        new_marker = MarkerStyle(self)
-        _transform = new_marker._user_transform or Affine2D()
-        new_marker._user_transform = _transform.translate(tx, ty)
-        return new_marker
-
     def _set_nothing(self):
         self._filled = False
 
diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
index 7925f22f54f7..f7f5d5614cac 100644
--- a/lib/matplotlib/tests/test_marker.py
+++ b/lib/matplotlib/tests/test_marker.py
@@ -253,20 +253,6 @@ def test_marker_rotated(marker, deg, rad, expected):
     assert marker._user_transform is not new_marker._user_transform
 
 
-def test_marker_translated():
-    marker = markers.MarkerStyle("1")
-    new_marker = marker.translated(1, 1)
-    assert new_marker is not marker
-    assert new_marker.get_user_transform() == Affine2D().translate(1, 1)
-    assert marker._user_transform is not new_marker._user_transform
-
-    marker = markers.MarkerStyle("1", transform=Affine2D().translate(1, 1))
-    new_marker = marker.translated(1, 1)
-    assert new_marker is not marker
-    assert new_marker.get_user_transform() == Affine2D().translate(2, 2)
-    assert marker._user_transform is not new_marker._user_transform
-
-
 def test_marker_scaled():
     marker = markers.MarkerStyle("1")
     new_marker = marker.scaled(2)

From 95d93d27a3e82a311d86e33007668c36e11cb745 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Wed, 15 Sep 2021 22:25:18 +0200
Subject: [PATCH 17/22] Add missing test for MarkerStyle.get_alt_transform

---
 lib/matplotlib/tests/test_marker.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
index f7f5d5614cac..d3665d9ce09d 100644
--- a/lib/matplotlib/tests/test_marker.py
+++ b/lib/matplotlib/tests/test_marker.py
@@ -271,3 +271,9 @@ def test_marker_scaled():
     expected = Affine2D().translate(1, 1).scale(2)
     assert new_marker.get_user_transform() == expected
     assert marker._user_transform is not new_marker._user_transform
+
+
+def test_alt_transform():
+    m1 = markers.MarkerStyle("o", "left")
+    m2 = markers.MarkerStyle("o", "left", Affine2D().rotate_deg(90))
+    assert m1.get_alt_transform().rotate_deg(90) == m2.get_alt_transform()

From 75a92d81edfb69c0da319ced1f9f1e8b590e4b1f Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Thu, 16 Sep 2021 23:02:53 +0200
Subject: [PATCH 18/22] Improve documentation outputs.

---
 examples/lines_bars_and_markers/marker_reference.py         | 1 +
 examples/lines_bars_and_markers/multivariate_marker_plot.py | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/examples/lines_bars_and_markers/marker_reference.py b/examples/lines_bars_and_markers/marker_reference.py
index f82ec36035e6..f751bfb975b8 100644
--- a/examples/lines_bars_and_markers/marker_reference.py
+++ b/examples/lines_bars_and_markers/marker_reference.py
@@ -197,6 +197,7 @@ def split_list(a_list):
     ax.text(x, 2.5, f"{theta}°", horizontalalignment="center")
 format_axes(ax)
 
+fig.tight_layout()
 plt.show()
 
 ###############################################################################
diff --git a/examples/lines_bars_and_markers/multivariate_marker_plot.py b/examples/lines_bars_and_markers/multivariate_marker_plot.py
index 51d7d4bca30e..0a79026b2772 100644
--- a/examples/lines_bars_and_markers/multivariate_marker_plot.py
+++ b/examples/lines_bars_and_markers/multivariate_marker_plot.py
@@ -43,3 +43,5 @@
              ax=ax, label="Normalized Thrust [a.u.]")
 ax.set_xlabel("X position [m]")
 ax.set_ylabel("Y position [m]")
+
+plt.show()

From e4f845643b0989ea6604e64181c1802ddc151aae Mon Sep 17 00:00:00 2001
From: Jakub Klus <48711526+deep-jkl@users.noreply.github.com>
Date: Tue, 28 Sep 2021 09:26:39 +0200
Subject: [PATCH 19/22] Update docstrings according to jklymak

Apply suggestions from @jklymak code review

Co-authored-by: Jody Klymak <jklymak@gmail.com>
---
 .../next_whats_new/extending_MarkerStyle.rst  |  5 ++--
 .../marker_reference.py                       | 14 ++++------
 .../multivariate_marker_plot.py               |  7 +++--
 lib/matplotlib/markers.py                     | 27 +++++++------------
 4 files changed, 20 insertions(+), 33 deletions(-)

diff --git a/doc/users/next_whats_new/extending_MarkerStyle.rst b/doc/users/next_whats_new/extending_MarkerStyle.rst
index fbe0fadd7f0c..6e970d0738fe 100644
--- a/doc/users/next_whats_new/extending_MarkerStyle.rst
+++ b/doc/users/next_whats_new/extending_MarkerStyle.rst
@@ -1,9 +1,8 @@
 New customization of MarkerStyle
 --------------------------------
 
-New MarkerStyle parameters allow control of join style and cap style. 
-The appearance of individual markers can be further controlled by 
-transform supplied during creation.
+New MarkerStyle parameters allow control of join style and cap style, and for
+the user to supply a transformation to be applied to the marker (e.g. a rotation).
 
 .. plot::
     :include-source: true
diff --git a/examples/lines_bars_and_markers/marker_reference.py b/examples/lines_bars_and_markers/marker_reference.py
index f751bfb975b8..ca9d1a77470a 100644
--- a/examples/lines_bars_and_markers/marker_reference.py
+++ b/examples/lines_bars_and_markers/marker_reference.py
@@ -166,10 +166,8 @@ def split_list(a_list):
 # Advanced marker modifications with transform
 # ============================================
 #
-# All markers can be modified by a user transform in MarkerStyle constructor.
-# Supplied transform is combined with the default transforms needed for
-# selected marker shape (e.g. caret up, caret down). Following example shows
-# how user supplied rotation applies to several marker shapes.
+# Markers can be modified by passing a transform to the MarkerStyle constructor.
+# Following example shows how a supplied rotation is applied to several marker shapes.
 
 common_style = {k: v for k, v in filled_marker_style.items() if k != 'marker'}
 angles = [0, 10, 20, 30, 45, 60, 90]
@@ -204,9 +202,8 @@ def split_list(a_list):
 # Setting marker cap style and join style
 # =======================================
 #
-# All markers have predefined cap style and join style, but this can be
-# overriden during creation of MarkerStyle. Follwing example show how to
-# change the cap style and how different styles look.
+# Markers have default cap and join styles, but these can be
+# customized when creating a MarkerStyle.
 
 from matplotlib.markers import JoinStyle, CapStyle
 
@@ -240,8 +237,7 @@ def split_list(a_list):
 plt.show()
 
 ###############################################################################
-# Follwing example show how to change the join style and how different styles
-# looks like.
+# Modifying the join style:
 
 fig, ax = plt.subplots()
 fig.suptitle('Marker JoinStyle', fontsize=14)
diff --git a/examples/lines_bars_and_markers/multivariate_marker_plot.py b/examples/lines_bars_and_markers/multivariate_marker_plot.py
index 0a79026b2772..284b21571d59 100644
--- a/examples/lines_bars_and_markers/multivariate_marker_plot.py
+++ b/examples/lines_bars_and_markers/multivariate_marker_plot.py
@@ -4,10 +4,9 @@
 ==============================================
 
 This example shows how to use different properties of markers to plot
-multivariate datasets. Following example shows an illustrative case of
-plotting success of baseball throw as an smiley face with size mapped to
-the skill of thrower, rotation mapped to the take-off angle, and thrust
-to the color of the marker.
+multivariate datasets. Here we represent a successful baseball throw as a smiley 
+face with marker size mapped to the skill of thrower, marker rotation to the take-off angle, 
+and thrust to the marker color.
 """
 
 import numpy as np
diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 6a839d040495..1436a8434d60 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -82,13 +82,9 @@
     plt.plot([1, 2, 3], marker=11)
     plt.plot([1, 2, 3], marker=matplotlib.markers.CARETDOWNBASE)
 
-Markers have some reasonable default settings for join and cap styles.
-However, those can be overriden when creating a new instance of MarkerStyle.
-Furthermore, the marker shape can be modified by supplying
-`~matplotlib.transforms.Transform` during creation.
-Some markers are created as internally rotated shapes (e.g. triangles).
-For such cases, both internal and user supplied transforms are combined.
-
+Markers join and cap styles can be customized by creating a new instance of MarkerStyle.
+A MarkerStyle can also have a custom
+`~matplotlib.transforms.Transform` allowing it to be arbitrarily rotated or offset.  
 Examples showing the use of markers:
 
 * :doc:`/gallery/lines_bars_and_markers/marker_reference`
@@ -253,16 +249,13 @@ def __init__(self, marker=_unset, fillstyle=None,
             One of 'full', 'left', 'right', 'bottom', 'top', 'none'.
 
         transform : Affine2D, default: None
-            User supplied transformation that will be combined with the
-            native transformation of selected marker.
+            Transform that will be combined with the native transform of the marker.
 
         capstyle : CapStyle, default: None
-            User supplied cap style that will override the default cap
-            style of selected marker.
+            Cap style that will override the default cap style of the marker.
 
         joinstyle : JoinStyle, default: None
-            User supplied join style that will override the default cap
-            style of selected marker.
+            Join style that will override the default join style of the marker.
         """
         self._marker_function = None
         self._user_transform = transform
@@ -431,7 +424,7 @@ def get_user_transform(self):
 
     def transformed(self, transform: Affine2D):
         """
-        Return new marker with combined transformation.
+        Return a new version of this marker with the transform applied. 
 
         Parameters
         ----------
@@ -447,15 +440,15 @@ def transformed(self, transform: Affine2D):
 
     def rotated(self, deg=None, rad=None):
         """
-        Return new marker rotated by specified angle.
+        Return a new version of this marker rotated by specified angle.
 
         Parameters
         ----------
         deg : float, default: None
-            Use this parameter to specify rotation angle in degrees.
+            Rotation angle in degrees.
 
         rad : float, default: None
-            Use this parameter to specify rotation angle in radians.
+            Rotation angle in radians.
 
         .. note:: You must specify exactly one of deg or rad.
         """

From 5aa5bbd071acd6285f43c387a6a8538ffa57520a Mon Sep 17 00:00:00 2001
From: Jakub Klus <48711526+deep-jkl@users.noreply.github.com>
Date: Tue, 28 Sep 2021 09:31:55 +0200
Subject: [PATCH 20/22] Make MarkerStyle.rotated more concise

Apply suggestions from code review

Co-authored-by: Jody Klymak <jklymak@gmail.com>
---
 lib/matplotlib/markers.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 1436a8434d60..a2189ea23d6a 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -438,7 +438,7 @@ def transformed(self, transform: Affine2D):
             new_marker._user_transform = transform
         return new_marker
 
-    def rotated(self, deg=None, rad=None):
+    def rotated(self, *, deg=None, rad=None):
         """
         Return a new version of this marker rotated by specified angle.
 
@@ -452,9 +452,10 @@ def rotated(self, deg=None, rad=None):
 
         .. note:: You must specify exactly one of deg or rad.
         """
-        if not (deg is None) ^ (rad is None):
-            raise ValueError("Exactly one of deg or rad shall be used.")
-
+        if deg is None and rad is None:
+            raise ValueError('One of deg or rad is required')
+        if deg is not None and rad is not None:
+            raise ValueError('Only one of deg and rad can be supplied')
         new_marker = MarkerStyle(self)
         if new_marker._user_transform is None:
             new_marker._user_transform = Affine2D()

From 214ea3f8fc9d6313c857ad6ffe8b13457a1a58d0 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Tue, 28 Sep 2021 10:37:44 +0200
Subject: [PATCH 21/22] Refactor code, linting.

---
 .../marker_reference.py                       |  5 +--
 .../multivariate_marker_plot.py               |  6 ++--
 lib/matplotlib/markers.py                     | 34 +++++++++----------
 3 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/examples/lines_bars_and_markers/marker_reference.py b/examples/lines_bars_and_markers/marker_reference.py
index ca9d1a77470a..c4564d2b027d 100644
--- a/examples/lines_bars_and_markers/marker_reference.py
+++ b/examples/lines_bars_and_markers/marker_reference.py
@@ -166,8 +166,9 @@ def split_list(a_list):
 # Advanced marker modifications with transform
 # ============================================
 #
-# Markers can be modified by passing a transform to the MarkerStyle constructor.
-# Following example shows how a supplied rotation is applied to several marker shapes.
+# Markers can be modified by passing a transform to the MarkerStyle
+# constructor. Following example shows how a supplied rotation is applied to
+# several marker shapes.
 
 common_style = {k: v for k, v in filled_marker_style.items() if k != 'marker'}
 angles = [0, 10, 20, 30, 45, 60, 90]
diff --git a/examples/lines_bars_and_markers/multivariate_marker_plot.py b/examples/lines_bars_and_markers/multivariate_marker_plot.py
index 284b21571d59..487bb2b85fd3 100644
--- a/examples/lines_bars_and_markers/multivariate_marker_plot.py
+++ b/examples/lines_bars_and_markers/multivariate_marker_plot.py
@@ -4,9 +4,9 @@
 ==============================================
 
 This example shows how to use different properties of markers to plot
-multivariate datasets. Here we represent a successful baseball throw as a smiley 
-face with marker size mapped to the skill of thrower, marker rotation to the take-off angle, 
-and thrust to the marker color.
+multivariate datasets. Here we represent a successful baseball throw as a
+smiley face with marker size mapped to the skill of thrower, marker rotation to
+the take-off angle, and thrust to the marker color.
 """
 
 import numpy as np
diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index a2189ea23d6a..85be6d7651bc 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -82,9 +82,11 @@
     plt.plot([1, 2, 3], marker=11)
     plt.plot([1, 2, 3], marker=matplotlib.markers.CARETDOWNBASE)
 
-Markers join and cap styles can be customized by creating a new instance of MarkerStyle.
-A MarkerStyle can also have a custom
-`~matplotlib.transforms.Transform` allowing it to be arbitrarily rotated or offset.  
+Markers join and cap styles can be customized by creating a new instance of
+MarkerStyle.
+A MarkerStyle can also have a custom `~matplotlib.transforms.Transform`
+allowing it to be arbitrarily rotated or offset.
+
 Examples showing the use of markers:
 
 * :doc:`/gallery/lines_bars_and_markers/marker_reference`
@@ -150,14 +152,6 @@
 _empty_path = Path(np.empty((0, 2)))
 
 
-def _fast_transform_combine(t1, t2):
-    """Combine two transformations where the second one can be None."""
-    if t2 is None:
-        return t1.frozen()
-    else:
-        return (t1 + t2).frozen()
-
-
 class MarkerStyle:
     """
     A class representing marker types.
@@ -248,8 +242,9 @@ def __init__(self, marker=_unset, fillstyle=None,
         fillstyle : str, default: :rc:`markers.fillstyle`
             One of 'full', 'left', 'right', 'bottom', 'top', 'none'.
 
-        transform : Affine2D, default: None
-            Transform that will be combined with the native transform of the marker.
+        transform : transforms.Transform, default: None
+            Transform that will be combined with the native transform of the
+            marker.
 
         capstyle : CapStyle, default: None
             Cap style that will override the default cap style of the marker.
@@ -395,7 +390,10 @@ def get_transform(self):
         Return the transform to be applied to the `.Path` from
         `MarkerStyle.get_path()`.
         """
-        return _fast_transform_combine(self._transform, self._user_transform)
+        if self._user_transform is None:
+            return self._transform.frozen()
+        else:
+            return (self._transform + self._user_transform).frozen()
 
     def get_alt_path(self):
         """
@@ -411,8 +409,10 @@ def get_alt_transform(self):
         Return the transform to be applied to the `.Path` from
         `MarkerStyle.get_alt_path()`.
         """
-        return _fast_transform_combine(self._alt_transform,
-                                       self._user_transform)
+        if self._user_transform is None:
+            return self._alt_transform.frozen()
+        else:
+            return (self._alt_transform + self._user_transform).frozen()
 
     def get_snap_threshold(self):
         return self._snap_threshold
@@ -424,7 +424,7 @@ def get_user_transform(self):
 
     def transformed(self, transform: Affine2D):
         """
-        Return a new version of this marker with the transform applied. 
+        Return a new version of this marker with the transform applied.
 
         Parameters
         ----------

From 7101e3c1216c48e65711a97926ccb56027d06c94 Mon Sep 17 00:00:00 2001
From: Jakub Klus <jakub.klus@gmail.com>
Date: Tue, 28 Sep 2021 15:30:05 +0200
Subject: [PATCH 22/22] Rework get_cap(join)style, add tests

Check for user style in get_cap(join)style is removed.
This is also supported with two new tests.
Additional test checks that get_transform returns combination of
supplied and internal transformation.
---
 lib/matplotlib/markers.py           |  4 ++--
 lib/matplotlib/tests/test_marker.py | 24 ++++++++++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/lib/matplotlib/markers.py b/lib/matplotlib/markers.py
index 85be6d7651bc..b1d6fa2be6a4 100644
--- a/lib/matplotlib/markers.py
+++ b/lib/matplotlib/markers.py
@@ -322,10 +322,10 @@ def _set_fillstyle(self, fillstyle):
         self._recache()
 
     def get_joinstyle(self):
-        return self._user_joinstyle or self._joinstyle
+        return self._joinstyle
 
     def get_capstyle(self):
-        return self._user_capstyle or self._capstyle
+        return self._capstyle
 
     def get_marker(self):
         return self._marker
diff --git a/lib/matplotlib/tests/test_marker.py b/lib/matplotlib/tests/test_marker.py
index d3665d9ce09d..894dead24e84 100644
--- a/lib/matplotlib/tests/test_marker.py
+++ b/lib/matplotlib/tests/test_marker.py
@@ -207,6 +207,30 @@ def test_marker_clipping(fig_ref, fig_test):
     ax_test.axis('off')
 
 
+def test_marker_init_transforms():
+    """Test that initializing marker with transform is a simple addition."""
+    marker = markers.MarkerStyle("o")
+    t = Affine2D().translate(1, 1)
+    t_marker = markers.MarkerStyle("o", transform=t)
+    assert marker.get_transform() + t == t_marker.get_transform()
+
+
+def test_marker_init_joinstyle():
+    marker = markers.MarkerStyle("*")
+    jstl = markers.JoinStyle.round
+    styled_marker = markers.MarkerStyle("*", joinstyle=jstl)
+    assert styled_marker.get_joinstyle() == jstl
+    assert marker.get_joinstyle() != jstl
+
+
+def test_marker_init_captyle():
+    marker = markers.MarkerStyle("*")
+    capstl = markers.CapStyle.round
+    styled_marker = markers.MarkerStyle("*", capstyle=capstl)
+    assert styled_marker.get_capstyle() == capstl
+    assert marker.get_capstyle() != capstl
+
+
 @pytest.mark.parametrize("marker,transform,expected", [
     (markers.MarkerStyle("o"), Affine2D().translate(1, 1),
         Affine2D().translate(1, 1)),

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