From 3476c7150beae51317d4a12078d9a71e154b675d Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Sun, 26 Jul 2020 10:14:48 +0100
Subject: [PATCH 1/3] Remove support for multiple-color strings in
 to_rgba_array

---
 lib/matplotlib/colors.py            | 19 +++----------------
 lib/matplotlib/tests/test_colors.py | 14 ++++----------
 2 files changed, 7 insertions(+), 26 deletions(-)

diff --git a/lib/matplotlib/colors.py b/lib/matplotlib/colors.py
index d6fd58c8bad9..3765145c3094 100644
--- a/lib/matplotlib/colors.py
+++ b/lib/matplotlib/colors.py
@@ -322,23 +322,10 @@ def to_rgba_array(c, alpha=None):
     except (ValueError, TypeError):
         pass
 
-    # Convert one at a time.
     if isinstance(c, str):
-        # Single string as color sequence.
-        # This is deprecated and will be removed in the future.
-        try:
-            result = np.array([to_rgba(cc, alpha) for cc in c])
-        except ValueError as err:
-            raise ValueError(
-                "'%s' is neither a valid single color nor a color sequence "
-                "consisting of single character color specifiers such as "
-                "'rgb'. Note also that the latter is deprecated." % c) from err
-        else:
-            cbook.warn_deprecated(
-                "3.2", message="Using a string of single character colors as "
-                "a color sequence is deprecated since %(since)s and will be "
-                "removed %(removal)s. Use an explicit list instead.")
-            return result
+        raise ValueError("Using a string of single character colors as "
+                         "a color sequence is not supported. The colors can "
+                         "be passed as an explicit list instead.")
 
     if len(c) == 0:
         return np.zeros((0, 4), float)
diff --git a/lib/matplotlib/tests/test_colors.py b/lib/matplotlib/tests/test_colors.py
index 0468d727e0df..5e0b2044bcf8 100644
--- a/lib/matplotlib/tests/test_colors.py
+++ b/lib/matplotlib/tests/test_colors.py
@@ -1057,17 +1057,11 @@ def test_to_rgba_array_single_str():
     # single color name is valid
     assert_array_equal(mcolors.to_rgba_array("red"), [(1, 0, 0, 1)])
 
-    # single char color sequence is deprecated
-    with pytest.warns(cbook.MatplotlibDeprecationWarning,
-                      match="Using a string of single character colors as a "
-                            "color sequence is deprecated"):
-        array = mcolors.to_rgba_array("rgb")
-    assert_array_equal(array, [(1, 0, 0, 1), (0, 0.5, 0, 1), (0, 0, 1, 1)])
-
+    # single char color sequence is invalid
     with pytest.raises(ValueError,
-                       match="neither a valid single color nor a color "
-                             "sequence"):
-        mcolors.to_rgba_array("rgbx")
+                       match="Using a string of single character colors as "
+                             "a color sequence is not supported."):
+        array = mcolors.to_rgba_array("rgb")
 
 
 def test_failed_conversions():

From 02e1396ffd5555f6de59884fc3646694b7a1e4f7 Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Sun, 26 Jul 2020 10:18:17 +0100
Subject: [PATCH 2/3] Add removal note

---
 doc/api/next_api_changes/removals/18069.DS.rst | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 doc/api/next_api_changes/removals/18069.DS.rst

diff --git a/doc/api/next_api_changes/removals/18069.DS.rst b/doc/api/next_api_changes/removals/18069.DS.rst
new file mode 100644
index 000000000000..07c93c97292e
--- /dev/null
+++ b/doc/api/next_api_changes/removals/18069.DS.rst
@@ -0,0 +1,5 @@
+Removed support for single color strings in `~.colors.to_rgba_array`
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Converting a string with single color characters (e.g. ``'rgb'``) in
+`~.colors.to_rgba_array`is no longer supported. Instead, the colors can be
+passed individually in a list (e.g. ``['r', 'g', 'b']``).

From 1e01d2810782de53824de90c770d8606c7220005 Mon Sep 17 00:00:00 2001
From: David Stansby <dstansby@gmail.com>
Date: Sun, 26 Jul 2020 11:28:28 +0100
Subject: [PATCH 3/3] Improve removal note

---
 doc/api/next_api_changes/removals/18069.DS.rst | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/doc/api/next_api_changes/removals/18069.DS.rst b/doc/api/next_api_changes/removals/18069.DS.rst
index 07c93c97292e..f55bf30bbd07 100644
--- a/doc/api/next_api_changes/removals/18069.DS.rst
+++ b/doc/api/next_api_changes/removals/18069.DS.rst
@@ -1,5 +1,5 @@
 Removed support for single color strings in `~.colors.to_rgba_array`
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Converting a string with single color characters (e.g. ``'rgb'``) in
-`~.colors.to_rgba_array`is no longer supported. Instead, the colors can be
-passed individually in a list (e.g. ``['r', 'g', 'b']``).
+Converting a string with single color characters (e.g. ``'cymk'``) in
+`~.colors.to_rgba_array` is no longer supported. Instead, the colors can be
+passed individually in a list (e.g. ``['c', 'y', 'm', 'k']``).