From 0f1b99ab34fbf6c81faf08e59768797a7dc7637e Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sat, 17 Oct 2020 23:16:28 +0700
Subject: [PATCH 01/24] REF: extract functions

---
 pandas/plotting/_matplotlib/style.py | 118 ++++++++++++++++++---------
 1 file changed, 79 insertions(+), 39 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index b919728971505..49c1436d7981d 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -3,6 +3,7 @@
 
 import matplotlib.cm as cm
 import matplotlib.colors
+import matplotlib.pyplot as plt
 import numpy as np
 
 from pandas.core.dtypes.common import is_list_like
@@ -11,55 +12,35 @@
 
 
 def get_standard_colors(
-    num_colors: int, colormap=None, color_type: str = "default", color=None
+    num_colors: int,
+    colormap=None,
+    color_type: str = "default",
+    color=None,
 ):
-    import matplotlib.pyplot as plt
+    colors = _get_colors(
+        color=color,
+        colormap=colormap,
+        color_type=color_type,
+        num_colors=num_colors,
+    )
 
+    return _cycle_colors(colors, num_colors=num_colors)
+
+
+def _get_colors(*, color, colormap, color_type, num_colors):
     if color is None and colormap is not None:
-        if isinstance(colormap, str):
-            cmap = colormap
-            colormap = cm.get_cmap(colormap)
-            if colormap is None:
-                raise ValueError(f"Colormap {cmap} is not recognized")
-        colors = [colormap(num) for num in np.linspace(0, 1, num=num_colors)]
+        return _get_colors_from_colormap(colormap, num_colors=num_colors)
     elif color is not None:
         if colormap is not None:
             warnings.warn(
                 "'color' and 'colormap' cannot be used simultaneously. Using 'color'"
             )
-        colors = (
-            list(color)
-            if is_list_like(color) and not isinstance(color, dict)
-            else color
-        )
+        return _get_colors_from_color(color)
     else:
-        if color_type == "default":
-            # need to call list() on the result to copy so we don't
-            # modify the global rcParams below
-            try:
-                colors = [c["color"] for c in list(plt.rcParams["axes.prop_cycle"])]
-            except KeyError:
-                colors = list(plt.rcParams.get("axes.color_cycle", list("bgrcmyk")))
-            if isinstance(colors, str):
-                colors = list(colors)
-
-            colors = colors[0:num_colors]
-        elif color_type == "random":
-
-            def random_color(column):
-                """ Returns a random color represented as a list of length 3"""
-                # GH17525 use common._random_state to avoid resetting the seed
-                rs = com.random_state(column)
-                return rs.rand(3).tolist()
-
-            colors = [random_color(num) for num in range(num_colors)]
-        else:
-            raise ValueError("color_type must be either 'default' or 'random'")
-
-    if isinstance(colors, str) and _is_single_color(colors):
-        # GH #36972
-        colors = [colors]
+        return _get_colors_from_color_type(color_type, num_colors=num_colors)
+
 
+def _cycle_colors(colors, num_colors):
     # Append more colors by cycling if there is not enough color.
     # Extra colors will be ignored by matplotlib if there are more colors
     # than needed and nothing needs to be done here.
@@ -76,6 +57,65 @@ def random_color(column):
     return colors
 
 
+def _get_colors_from_colormap(colormap, num_colors):
+    colormap = _get_cmap_instance(colormap)
+    return [colormap(num) for num in np.linspace(0, 1, num=num_colors)]
+
+
+def _get_cmap_instance(colormap):
+    if isinstance(colormap, str):
+        cmap = colormap
+        colormap = cm.get_cmap(colormap)
+        if colormap is None:
+            raise ValueError(f"Colormap {cmap} is not recognized")
+    return colormap
+
+
+def _get_colors_from_color(color):
+    if is_list_like(color) and not isinstance(color, dict):
+        return list(color)
+
+    if _is_single_color(color):
+        # GH #36972
+        return [color]
+
+    return color
+
+
+def _get_colors_from_color_type(color_type, num_colors):
+    if color_type == "default":
+        return _get_default_colors(num_colors)
+    elif color_type == "random":
+        return _get_random_colors(num_colors)
+    else:
+        raise ValueError("color_type must be either 'default' or 'random'")
+
+
+def _get_default_colors(num_colors):
+    # need to call list() on the result to copy so we don't
+    # modify the global rcParams below
+    try:
+        colors = [c["color"] for c in list(plt.rcParams["axes.prop_cycle"])]
+    except KeyError:
+        colors = list(plt.rcParams.get("axes.color_cycle", list("bgrcmyk")))
+
+    if isinstance(colors, str):
+        colors = list(colors)
+
+    return colors[0:num_colors]
+
+
+def _get_random_colors(num_colors):
+    return [_random_color(num) for num in range(num_colors)]
+
+
+def _random_color(column):
+    """ Returns a random color represented as a list of length 3"""
+    # GH17525 use common._random_state to avoid resetting the seed
+    rs = com.random_state(column)
+    return rs.rand(3).tolist()
+
+
 def _is_single_color(color: str) -> bool:
     """Check if ``color`` is a single color.
 

From 901453a06b8be5445272155bba92e6e4a2fb8acb Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sat, 17 Oct 2020 23:35:04 +0700
Subject: [PATCH 02/24] CLN: remove try/except/ZeroDivisionError

---
 pandas/plotting/_matplotlib/style.py | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 49c1436d7981d..cadd1377d7978 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -45,12 +45,8 @@ def _cycle_colors(colors, num_colors):
     # Extra colors will be ignored by matplotlib if there are more colors
     # than needed and nothing needs to be done here.
     if len(colors) < num_colors:
-        try:
-            multiple = num_colors // len(colors) - 1
-        except ZeroDivisionError:
-            raise ValueError("Invalid color argument: ''")
+        multiple = num_colors // len(colors) - 1
         mod = num_colors % len(colors)
-
         colors += multiple * colors
         colors += colors[:mod]
 
@@ -72,6 +68,9 @@ def _get_cmap_instance(colormap):
 
 
 def _get_colors_from_color(color):
+    if len(color) == 0:
+        raise ValueError("Invalid color argument: {color}")
+
     if is_list_like(color) and not isinstance(color, dict):
         return list(color)
 

From 201b25f519cb302516f128205ffa7172de42245d Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sat, 17 Oct 2020 23:38:44 +0700
Subject: [PATCH 03/24] REF: drop unnecesasry if statement

---
 pandas/plotting/_matplotlib/style.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index cadd1377d7978..eefa16dc15761 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -98,9 +98,6 @@ def _get_default_colors(num_colors):
     except KeyError:
         colors = list(plt.rcParams.get("axes.color_cycle", list("bgrcmyk")))
 
-    if isinstance(colors, str):
-        colors = list(colors)
-
     return colors[0:num_colors]
 
 

From 8e13df506d6fa8f143efa84473342c46984be138 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sat, 17 Oct 2020 23:40:43 +0700
Subject: [PATCH 04/24] CLN: simplify logic

---
 pandas/plotting/_matplotlib/style.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index eefa16dc15761..68e6e6d2c6073 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -71,7 +71,10 @@ def _get_colors_from_color(color):
     if len(color) == 0:
         raise ValueError("Invalid color argument: {color}")
 
-    if is_list_like(color) and not isinstance(color, dict):
+    if isinstance(color, dict):
+        return color
+
+    if is_list_like(color):
         return list(color)
 
     if _is_single_color(color):

From 37a820dda478d7e119346c5069c8cd5007d4fa1b Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sat, 17 Oct 2020 23:43:45 +0700
Subject: [PATCH 05/24] DOC: add short docstrings

---
 pandas/plotting/_matplotlib/style.py | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 68e6e6d2c6073..9f17f0236c414 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -28,6 +28,7 @@ def get_standard_colors(
 
 
 def _get_colors(*, color, colormap, color_type, num_colors):
+    """Get colors from user input."""
     if color is None and colormap is not None:
         return _get_colors_from_colormap(colormap, num_colors=num_colors)
     elif color is not None:
@@ -41,9 +42,11 @@ def _get_colors(*, color, colormap, color_type, num_colors):
 
 
 def _cycle_colors(colors, num_colors):
-    # Append more colors by cycling if there is not enough color.
-    # Extra colors will be ignored by matplotlib if there are more colors
-    # than needed and nothing needs to be done here.
+    """Append more colors by cycling if there is not enough color.
+
+    Extra colors will be ignored by matplotlib if there are more colors
+    than needed and nothing needs to be done here.
+    """
     if len(colors) < num_colors:
         multiple = num_colors // len(colors) - 1
         mod = num_colors % len(colors)
@@ -54,11 +57,13 @@ def _cycle_colors(colors, num_colors):
 
 
 def _get_colors_from_colormap(colormap, num_colors):
+    """Get colors from colormap."""
     colormap = _get_cmap_instance(colormap)
     return [colormap(num) for num in np.linspace(0, 1, num=num_colors)]
 
 
 def _get_cmap_instance(colormap):
+    """Get instance of matplotlib colormap."""
     if isinstance(colormap, str):
         cmap = colormap
         colormap = cm.get_cmap(colormap)
@@ -68,6 +73,7 @@ def _get_cmap_instance(colormap):
 
 
 def _get_colors_from_color(color):
+    """Get colors from user input color."""
     if len(color) == 0:
         raise ValueError("Invalid color argument: {color}")
 
@@ -85,6 +91,7 @@ def _get_colors_from_color(color):
 
 
 def _get_colors_from_color_type(color_type, num_colors):
+    """Get colors from user input color type."""
     if color_type == "default":
         return _get_default_colors(num_colors)
     elif color_type == "random":
@@ -94,6 +101,7 @@ def _get_colors_from_color_type(color_type, num_colors):
 
 
 def _get_default_colors(num_colors):
+    """Get ``num_colors`` of default colors from matplotlib rc params."""
     # need to call list() on the result to copy so we don't
     # modify the global rcParams below
     try:
@@ -105,11 +113,12 @@ def _get_default_colors(num_colors):
 
 
 def _get_random_colors(num_colors):
+    """Get ``num_colors`` of random colors."""
     return [_random_color(num) for num in range(num_colors)]
 
 
 def _random_color(column):
-    """ Returns a random color represented as a list of length 3"""
+    """Get a random color represented as a list of length 3"""
     # GH17525 use common._random_state to avoid resetting the seed
     rs = com.random_state(column)
     return rs.rand(3).tolist()

From 3883a1381572daa4afa533f62fbf7780889d4636 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 00:06:21 +0700
Subject: [PATCH 06/24] CLN: simplify logic further

---
 pandas/plotting/_matplotlib/style.py | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 9f17f0236c414..a28e1e66ad775 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -6,7 +6,6 @@
 import matplotlib.pyplot as plt
 import numpy as np
 
-from pandas.core.dtypes.common import is_list_like
 
 import pandas.core.common as com
 
@@ -80,14 +79,11 @@ def _get_colors_from_color(color):
     if isinstance(color, dict):
         return color
 
-    if is_list_like(color):
-        return list(color)
-
     if _is_single_color(color):
         # GH #36972
         return [color]
 
-    return color
+    return list(color)
 
 
 def _get_colors_from_color_type(color_type, num_colors):

From f93743c1eb0214346920c4fbfd2ffd18a6fa0775 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 01:13:39 +0700
Subject: [PATCH 07/24] TYP: add type annotations

---
 pandas/plotting/_matplotlib/style.py | 64 +++++++++++++++++++++-------
 1 file changed, 49 insertions(+), 15 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index a28e1e66ad775..63762f6578e3b 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -1,4 +1,13 @@
-# being a bit too dynamic
+from typing import (
+    TYPE_CHECKING,
+    Collection,
+    Dict,
+    Iterable,
+    List,
+    Optional,
+    Sequence,
+    Union,
+)
 import warnings
 
 import matplotlib.cm as cm
@@ -6,9 +15,14 @@
 import matplotlib.pyplot as plt
 import numpy as np
 
-
 import pandas.core.common as com
 
+if TYPE_CHECKING:
+    from matplotlib.colors import Colormap
+
+
+Color = Union[str, Sequence[float]]
+
 
 def get_standard_colors(
     num_colors: int,
@@ -23,10 +37,19 @@ def get_standard_colors(
         num_colors=num_colors,
     )
 
-    return _cycle_colors(colors, num_colors=num_colors)
+    if isinstance(colors, dict):
+        return colors
 
+    return _cycle_colors(list(colors), num_colors=num_colors)
 
-def _get_colors(*, color, colormap, color_type, num_colors):
+
+def _get_colors(
+    *,
+    color: Optional[Union[Color, Dict[str, Color], Collection[Color]]],
+    colormap: Optional[Union[str, "Colormap"]],
+    color_type: str,
+    num_colors: int,
+) -> Union[Dict[str, Color], Collection[Color]]:
     """Get colors from user input."""
     if color is None and colormap is not None:
         return _get_colors_from_colormap(colormap, num_colors=num_colors)
@@ -40,7 +63,7 @@ def _get_colors(*, color, colormap, color_type, num_colors):
         return _get_colors_from_color_type(color_type, num_colors=num_colors)
 
 
-def _cycle_colors(colors, num_colors):
+def _cycle_colors(colors: List[Color], num_colors: int) -> List[Color]:
     """Append more colors by cycling if there is not enough color.
 
     Extra colors will be ignored by matplotlib if there are more colors
@@ -55,13 +78,16 @@ def _cycle_colors(colors, num_colors):
     return colors
 
 
-def _get_colors_from_colormap(colormap, num_colors):
+def _get_colors_from_colormap(
+    colormap: Union[str, "Colormap"],
+    num_colors: int,
+) -> Collection[Color]:
     """Get colors from colormap."""
     colormap = _get_cmap_instance(colormap)
     return [colormap(num) for num in np.linspace(0, 1, num=num_colors)]
 
 
-def _get_cmap_instance(colormap):
+def _get_cmap_instance(colormap: Union[str, "Colormap"]) -> "Colormap":
     """Get instance of matplotlib colormap."""
     if isinstance(colormap, str):
         cmap = colormap
@@ -71,22 +97,30 @@ def _get_cmap_instance(colormap):
     return colormap
 
 
-def _get_colors_from_color(color):
+def _get_colors_from_color(
+    color: Union[Color, Dict[str, Color], Collection[Color]],
+) -> Union[Dict[str, Color], Collection[Color]]:
     """Get colors from user input color."""
-    if len(color) == 0:
+    if isinstance(color, Iterable) and len(color) == 0:
         raise ValueError("Invalid color argument: {color}")
 
     if isinstance(color, dict):
         return color
 
-    if _is_single_color(color):
+    if isinstance(color, str) and _is_single_color(color):
         # GH #36972
         return [color]
 
-    return list(color)
+    # ignoring mypy error here
+    # error: Argument 1 to "list" has incompatible type
+    # "Union[Sequence[float], Collection[Union[str, Sequence[float]]]]";
+    # expected "Iterable[Union[str, Sequence[float]]]"  [arg-type]
+    # A this point color may be string with multiple letters,
+    # sequence of floats or series of colors, all convertible to list
+    return list(color)  # type: ignore [arg-type]
 
 
-def _get_colors_from_color_type(color_type, num_colors):
+def _get_colors_from_color_type(color_type: str, num_colors: int) -> Collection[Color]:
     """Get colors from user input color type."""
     if color_type == "default":
         return _get_default_colors(num_colors)
@@ -96,7 +130,7 @@ def _get_colors_from_color_type(color_type, num_colors):
         raise ValueError("color_type must be either 'default' or 'random'")
 
 
-def _get_default_colors(num_colors):
+def _get_default_colors(num_colors: int) -> Collection[Color]:
     """Get ``num_colors`` of default colors from matplotlib rc params."""
     # need to call list() on the result to copy so we don't
     # modify the global rcParams below
@@ -108,12 +142,12 @@ def _get_default_colors(num_colors):
     return colors[0:num_colors]
 
 
-def _get_random_colors(num_colors):
+def _get_random_colors(num_colors: int) -> Sequence[Sequence[float]]:
     """Get ``num_colors`` of random colors."""
     return [_random_color(num) for num in range(num_colors)]
 
 
-def _random_color(column):
+def _random_color(column: int) -> Sequence[float]:
     """Get a random color represented as a list of length 3"""
     # GH17525 use common._random_state to avoid resetting the seed
     rs = com.random_state(column)

From b4c32673cd73f3e5052aa33f7c2120e17cbdc99b Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 01:58:29 +0700
Subject: [PATCH 08/24] REF: more explicitly handle string color

---
 pandas/plotting/_matplotlib/style.py | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 63762f6578e3b..9d06f3cb96638 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -107,16 +107,19 @@ def _get_colors_from_color(
     if isinstance(color, dict):
         return color
 
-    if isinstance(color, str) and _is_single_color(color):
-        # GH #36972
-        return [color]
+    if isinstance(color, str):
+        if _is_single_color(color):
+            # GH #36972
+            return [color]
+        else:
+            return list(color)
 
     # ignoring mypy error here
     # error: Argument 1 to "list" has incompatible type
     # "Union[Sequence[float], Collection[Union[str, Sequence[float]]]]";
     # expected "Iterable[Union[str, Sequence[float]]]"  [arg-type]
-    # A this point color may be string with multiple letters,
-    # sequence of floats or series of colors, all convertible to list
+    # A this point color may be sequence of floats or series of colors,
+    # all convertible to list
     return list(color)  # type: ignore [arg-type]
 
 

From 6af1543af84ef7f4b68923be0af69f6d0e64cab3 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 01:58:47 +0700
Subject: [PATCH 09/24] FIX: fix mpl registry reset

---
 pandas/plotting/_matplotlib/style.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 9d06f3cb96638..52c827ca96f51 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -12,7 +12,6 @@
 
 import matplotlib.cm as cm
 import matplotlib.colors
-import matplotlib.pyplot as plt
 import numpy as np
 
 import pandas.core.common as com
@@ -135,6 +134,8 @@ def _get_colors_from_color_type(color_type: str, num_colors: int) -> Collection[
 
 def _get_default_colors(num_colors: int) -> Collection[Color]:
     """Get ``num_colors`` of default colors from matplotlib rc params."""
+    import matplotlib.pyplot as plt
+
     # need to call list() on the result to copy so we don't
     # modify the global rcParams below
     try:

From 31125f7542d4a58f1e47825a363632659e826c03 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 20:01:58 +0700
Subject: [PATCH 10/24] TYP: fix typing in _get_colors_from_color

---
 pandas/plotting/_matplotlib/style.py | 71 ++++++++++++++++------------
 1 file changed, 41 insertions(+), 30 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 52c827ca96f51..1a3f853fc1db6 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -1,12 +1,11 @@
 from typing import (
     TYPE_CHECKING,
     Collection,
-    Dict,
-    Iterable,
     List,
     Optional,
     Sequence,
     Union,
+    cast,
 )
 import warnings
 
@@ -15,6 +14,7 @@
 import numpy as np
 
 import pandas.core.common as com
+from pandas.core.dtypes.common import is_list_like
 
 if TYPE_CHECKING:
     from matplotlib.colors import Colormap
@@ -29,6 +29,9 @@ def get_standard_colors(
     color_type: str = "default",
     color=None,
 ):
+    if isinstance(color, dict):
+        return color
+
     colors = _get_colors(
         color=color,
         colormap=colormap,
@@ -36,19 +39,16 @@ def get_standard_colors(
         num_colors=num_colors,
     )
 
-    if isinstance(colors, dict):
-        return colors
-
-    return _cycle_colors(list(colors), num_colors=num_colors)
+    return _cycle_colors(colors, num_colors=num_colors)
 
 
 def _get_colors(
     *,
-    color: Optional[Union[Color, Dict[str, Color], Collection[Color]]],
+    color: Optional[Union[Color, Collection[Color]]],
     colormap: Optional[Union[str, "Colormap"]],
     color_type: str,
     num_colors: int,
-) -> Union[Dict[str, Color], Collection[Color]]:
+) -> List[Color]:
     """Get colors from user input."""
     if color is None and colormap is not None:
         return _get_colors_from_colormap(colormap, num_colors=num_colors)
@@ -80,7 +80,7 @@ def _cycle_colors(colors: List[Color], num_colors: int) -> List[Color]:
 def _get_colors_from_colormap(
     colormap: Union[str, "Colormap"],
     num_colors: int,
-) -> Collection[Color]:
+) -> List[Color]:
     """Get colors from colormap."""
     colormap = _get_cmap_instance(colormap)
     return [colormap(num) for num in np.linspace(0, 1, num=num_colors)]
@@ -97,14 +97,11 @@ def _get_cmap_instance(colormap: Union[str, "Colormap"]) -> "Colormap":
 
 
 def _get_colors_from_color(
-    color: Union[Color, Dict[str, Color], Collection[Color]],
-) -> Union[Dict[str, Color], Collection[Color]]:
+    color: Union[Color, Collection[Color]],
+) -> List[Color]:
     """Get colors from user input color."""
-    if isinstance(color, Iterable) and len(color) == 0:
-        raise ValueError("Invalid color argument: {color}")
-
-    if isinstance(color, dict):
-        return color
+    if len(color) == 0:
+        raise ValueError(f"Invalid color argument: {color}")
 
     if isinstance(color, str):
         if _is_single_color(color):
@@ -113,16 +110,30 @@ def _get_colors_from_color(
         else:
             return list(color)
 
-    # ignoring mypy error here
-    # error: Argument 1 to "list" has incompatible type
-    # "Union[Sequence[float], Collection[Union[str, Sequence[float]]]]";
-    # expected "Iterable[Union[str, Sequence[float]]]"  [arg-type]
-    # A this point color may be sequence of floats or series of colors,
-    # all convertible to list
-    return list(color)  # type: ignore [arg-type]
+    if _is_floats_color(color):
+        color = cast(Sequence[float], color)
+        return [color]
+
+    color = cast(Collection[Color], color)
+    colors = []
+    for x in color:
+        if _is_single_color(x):
+            colors.append(x)
+        else:
+            raise ValueError(f"Invalid color {x}")
+    return colors
+
+
+def _is_floats_color(color: Union[Color, Collection[Color]]) -> bool:
+    """Check if color comprises a sequence of floats representing color."""
+    return bool(
+        is_list_like(color)
+        and (len(color) == 3 or len(color) == 4)
+        and all([isinstance(x, float) for x in color])
+    )
 
 
-def _get_colors_from_color_type(color_type: str, num_colors: int) -> Collection[Color]:
+def _get_colors_from_color_type(color_type: str, num_colors: int) -> List[Color]:
     """Get colors from user input color type."""
     if color_type == "default":
         return _get_default_colors(num_colors)
@@ -132,7 +143,7 @@ def _get_colors_from_color_type(color_type: str, num_colors: int) -> Collection[
         raise ValueError("color_type must be either 'default' or 'random'")
 
 
-def _get_default_colors(num_colors: int) -> Collection[Color]:
+def _get_default_colors(num_colors: int) -> List[Color]:
     """Get ``num_colors`` of default colors from matplotlib rc params."""
     import matplotlib.pyplot as plt
 
@@ -146,19 +157,19 @@ def _get_default_colors(num_colors: int) -> Collection[Color]:
     return colors[0:num_colors]
 
 
-def _get_random_colors(num_colors: int) -> Sequence[Sequence[float]]:
+def _get_random_colors(num_colors: int) -> List[Color]:
     """Get ``num_colors`` of random colors."""
     return [_random_color(num) for num in range(num_colors)]
 
 
-def _random_color(column: int) -> Sequence[float]:
+def _random_color(column: int) -> List[float]:
     """Get a random color represented as a list of length 3"""
     # GH17525 use common._random_state to avoid resetting the seed
     rs = com.random_state(column)
     return rs.rand(3).tolist()
 
 
-def _is_single_color(color: str) -> bool:
+def _is_single_color(color: Color) -> bool:
     """Check if ``color`` is a single color.
 
     Examples of single colors:
@@ -170,8 +181,8 @@ def _is_single_color(color: str) -> bool:
 
     Parameters
     ----------
-    color : string
-        Color string.
+    color : Color
+        Color string or sequence of floats.
 
     Returns
     -------

From 45647a49b09704b292b1eb86ec5786b30dc1fcd2 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 20:10:48 +0700
Subject: [PATCH 11/24] CLN: eliminate use of legacy "axes.color_cycle"

It turns out that even if "axes.prop_cycle" is not defined,
then it will be composed of CN colors (hex notation).
However, in the current matplotlib there is no "axes.color_cycle"
property in rcParams at all (not even allowed to setup).
---
 pandas/plotting/_matplotlib/style.py | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 1a3f853fc1db6..095b8755b021d 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -147,13 +147,7 @@ def _get_default_colors(num_colors: int) -> List[Color]:
     """Get ``num_colors`` of default colors from matplotlib rc params."""
     import matplotlib.pyplot as plt
 
-    # need to call list() on the result to copy so we don't
-    # modify the global rcParams below
-    try:
-        colors = [c["color"] for c in list(plt.rcParams["axes.prop_cycle"])]
-    except KeyError:
-        colors = list(plt.rcParams.get("axes.color_cycle", list("bgrcmyk")))
-
+    colors = [c["color"] for c in plt.rcParams["axes.prop_cycle"]]
     return colors[0:num_colors]
 
 

From 393ae463077d7c4010d94f83381471563dacdcaa Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 20:49:03 +0700
Subject: [PATCH 12/24] REF: extract generator function to simplify logic

---
 pandas/plotting/_matplotlib/style.py | 28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 095b8755b021d..8e531f59e6a46 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -1,6 +1,7 @@
 from typing import (
     TYPE_CHECKING,
     Collection,
+    Iterator,
     List,
     Optional,
     Sequence,
@@ -13,9 +14,10 @@
 import matplotlib.colors
 import numpy as np
 
-import pandas.core.common as com
 from pandas.core.dtypes.common import is_list_like
 
+import pandas.core.common as com
+
 if TYPE_CHECKING:
     from matplotlib.colors import Colormap
 
@@ -103,25 +105,30 @@ def _get_colors_from_color(
     if len(color) == 0:
         raise ValueError(f"Invalid color argument: {color}")
 
-    if isinstance(color, str):
-        if _is_single_color(color):
-            # GH #36972
-            return [color]
-        else:
-            return list(color)
+    if isinstance(color, str) and _is_single_color(color):
+        # GH #36972
+        return [color]
 
     if _is_floats_color(color):
         color = cast(Sequence[float], color)
         return [color]
 
     color = cast(Collection[Color], color)
-    colors = []
+    return list(_gen_list_of_colors_from_iterable(color))
+
+
+def _gen_list_of_colors_from_iterable(color: Collection[Color]) -> Iterator[Color]:
+    """
+    Yield colors from string of several letters or from collection of colors.
+    """
     for x in color:
+        if isinstance(x, str):
+            # to avoid warnings on upper case single letter colors
+            x = x.lower()
         if _is_single_color(x):
-            colors.append(x)
+            yield x
         else:
             raise ValueError(f"Invalid color {x}")
-    return colors
 
 
 def _is_floats_color(color: Union[Color, Collection[Color]]) -> bool:
@@ -172,6 +179,7 @@ def _is_single_color(color: Color) -> bool:
         - 'red'
         - 'green'
         - 'C3'
+        - 'firebrick'
 
     Parameters
     ----------

From fe66213f9b3296b18092257be3b6662cb8f78e89 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 20:51:32 +0700
Subject: [PATCH 13/24] TST: add tests for get_standard_colors

---
 pandas/tests/plotting/test_style.py | 150 ++++++++++++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 pandas/tests/plotting/test_style.py

diff --git a/pandas/tests/plotting/test_style.py b/pandas/tests/plotting/test_style.py
new file mode 100644
index 0000000000000..cbb8a75bbe310
--- /dev/null
+++ b/pandas/tests/plotting/test_style.py
@@ -0,0 +1,150 @@
+from cycler import cycler
+import matplotlib as mpl
+import matplotlib.colors
+import pytest
+
+from pandas import Series
+
+from pandas.plotting._matplotlib.style import get_standard_colors
+
+
+class TestGetStandardColors:
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (3, ["red", "green", "blue"]),
+            (5, ["red", "green", "blue", "red", "green"]),
+            (7, ["red", "green", "blue", "red", "green", "blue", "red"]),
+            (2, ["red", "green"]),
+            (1, ["red"]),
+        ],
+    )
+    def test_default_colors_named_from_prop_cycle(self, num_colors, expected):
+        mpl_params = {
+            "axes.prop_cycle": cycler(color=["red", "green", "blue"]),
+        }
+        with mpl.rc_context(rc=mpl_params):
+            result = get_standard_colors(num_colors=num_colors)
+            assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, ["b"]),
+            (3, ["b", "g", "r"]),
+            (4, ["b", "g", "r", "y"]),
+            (5, ["b", "g", "r", "y", "b"]),
+            (7, ["b", "g", "r", "y", "b", "g", "r"]),
+        ],
+    )
+    def test_default_colors_named_from_prop_cycle_string(self, num_colors, expected):
+        mpl_params = {
+            "axes.prop_cycle": cycler(color="bgry"),
+        }
+        with mpl.rc_context(rc=mpl_params):
+            result = get_standard_colors(num_colors=num_colors)
+            assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected_name",
+        [
+            (1, ["C0"]),
+            (3, ["C0", "C1", "C2"]),
+            (
+                12,
+                [
+                    "C0",
+                    "C1",
+                    "C2",
+                    "C3",
+                    "C4",
+                    "C5",
+                    "C6",
+                    "C7",
+                    "C8",
+                    "C9",
+                    "C0",
+                    "C1",
+                ],
+            ),
+        ],
+    )
+    def test_default_colors_named_undefined_prop_cycle(self, num_colors, expected_name):
+        with mpl.rc_context(rc={}):
+            expected = [matplotlib.colors.to_hex(x) for x in expected_name]
+            result = get_standard_colors(num_colors=num_colors)
+            assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, ["red", "green", (0.1, 0.2, 0.3)]),
+            (2, ["red", "green", (0.1, 0.2, 0.3)]),
+            (3, ["red", "green", (0.1, 0.2, 0.3)]),
+            (4, ["red", "green", (0.1, 0.2, 0.3), "red"]),
+        ],
+    )
+    def test_user_input_color_sequence(self, num_colors, expected):
+        color = ["red", "green", (0.1, 0.2, 0.3)]
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, ["r", "g", "b", "k"]),
+            (2, ["r", "g", "b", "k"]),
+            (3, ["r", "g", "b", "k"]),
+            (4, ["r", "g", "b", "k"]),
+            (5, ["r", "g", "b", "k", "r"]),
+            (6, ["r", "g", "b", "k", "r", "g"]),
+        ],
+    )
+    def test_user_input_color_string(self, num_colors, expected):
+        color = "rgbk"
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, [(0.1, 0.2, 0.3)]),
+            (2, [(0.1, 0.2, 0.3), (0.1, 0.2, 0.3)]),
+            (3, [(0.1, 0.2, 0.3), (0.1, 0.2, 0.3), (0.1, 0.2, 0.3)]),
+        ],
+    )
+    def test_user_input_color_floats(self, num_colors, expected):
+        color = (0.1, 0.2, 0.3)
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize(
+        "color, num_colors, expected",
+        [
+            ("Crimson", 1, ["Crimson"]),
+            ("DodgerBlue", 2, ["DodgerBlue", "DodgerBlue"]),
+            ("firebrick", 3, ["firebrick", "firebrick", "firebrick"]),
+        ],
+    )
+    def test_user_input_named_color_string(self, color, num_colors, expected):
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize("color", ["", [], (), Series([], dtype="object")])
+    def test_empty_color_raises(self, color):
+        with pytest.raises(ValueError, match="Invalid color argument"):
+            get_standard_colors(color=color, num_colors=1)
+
+    @pytest.mark.parametrize(
+        "color",
+        [
+            "BAD_COLOR",
+            ("red", "green", "BAD_COLOR"),
+            (0.1,),
+            (0.1, 0.2),
+            (0.1, 0.2, 0.3, 0.4, 0.5),  # must be either 3 or 4 floats
+        ],
+    )
+    def test_bad_color_raises(self, color):
+        with pytest.raises(ValueError, match="Invalid color"):
+            get_standard_colors(color=color, num_colors=5)

From 1626108adfa7075edb137e57aadd4b6542dcd1c3 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 20:53:42 +0700
Subject: [PATCH 14/24] CLN: drop list comprehension for generator expr

---
 pandas/plotting/_matplotlib/style.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 8e531f59e6a46..44709b486e2bf 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -136,7 +136,7 @@ def _is_floats_color(color: Union[Color, Collection[Color]]) -> bool:
     return bool(
         is_list_like(color)
         and (len(color) == 3 or len(color) == 4)
-        and all([isinstance(x, float) for x in color])
+        and all(isinstance(x, float) for x in color)
     )
 
 

From 79b0f08cf4c0b050f3c92103872d8a089b6f89c9 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 20:58:12 +0700
Subject: [PATCH 15/24] TYP: annotate get_standard_colors

---
 pandas/plotting/_matplotlib/style.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index 44709b486e2bf..da4111456a4d3 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -1,6 +1,7 @@
 from typing import (
     TYPE_CHECKING,
     Collection,
+    Dict,
     Iterator,
     List,
     Optional,
@@ -27,9 +28,9 @@
 
 def get_standard_colors(
     num_colors: int,
-    colormap=None,
+    colormap: Optional["Colormap"] = None,
     color_type: str = "default",
-    color=None,
+    color: Optional[Union[Dict[str, Color], Color, Collection[Color]]] = None,
 ):
     if isinstance(color, dict):
         return color

From f513bdb069d2650b89a07c31cc33ed4b1ae7268a Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 21:36:24 +0700
Subject: [PATCH 16/24] DEP: add testing dependency (cycler)

---
 environment.yml                      |  1 +
 pandas/plotting/_matplotlib/style.py |  3 ---
 pandas/tests/plotting/test_style.py  | 15 ++++++++++-----
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/environment.yml b/environment.yml
index 77a9c5fd4822d..7efb12ffb6b19 100644
--- a/environment.yml
+++ b/environment.yml
@@ -52,6 +52,7 @@ dependencies:
   - botocore>=1.11
   - hypothesis>=3.82
   - moto  # mock S3
+  - cycler  # test matplotlib colors cycle
   - flask
   - pytest>=5.0.1
   - pytest-cov
diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index da4111456a4d3..b8f162008f852 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -123,9 +123,6 @@ def _gen_list_of_colors_from_iterable(color: Collection[Color]) -> Iterator[Colo
     Yield colors from string of several letters or from collection of colors.
     """
     for x in color:
-        if isinstance(x, str):
-            # to avoid warnings on upper case single letter colors
-            x = x.lower()
         if _is_single_color(x):
             yield x
         else:
diff --git a/pandas/tests/plotting/test_style.py b/pandas/tests/plotting/test_style.py
index cbb8a75bbe310..7fb041b44acb6 100644
--- a/pandas/tests/plotting/test_style.py
+++ b/pandas/tests/plotting/test_style.py
@@ -1,6 +1,4 @@
 from cycler import cycler
-import matplotlib as mpl
-import matplotlib.colors
 import pytest
 
 from pandas import Series
@@ -20,6 +18,8 @@ class TestGetStandardColors:
         ],
     )
     def test_default_colors_named_from_prop_cycle(self, num_colors, expected):
+        import matplotlib as mpl
+
         mpl_params = {
             "axes.prop_cycle": cycler(color=["red", "green", "blue"]),
         }
@@ -38,6 +38,8 @@ def test_default_colors_named_from_prop_cycle(self, num_colors, expected):
         ],
     )
     def test_default_colors_named_from_prop_cycle_string(self, num_colors, expected):
+        import matplotlib as mpl
+
         mpl_params = {
             "axes.prop_cycle": cycler(color="bgry"),
         }
@@ -70,8 +72,11 @@ def test_default_colors_named_from_prop_cycle_string(self, num_colors, expected)
         ],
     )
     def test_default_colors_named_undefined_prop_cycle(self, num_colors, expected_name):
+        import matplotlib as mpl
+        import matplotlib.colors as mcolors
+
         with mpl.rc_context(rc={}):
-            expected = [matplotlib.colors.to_hex(x) for x in expected_name]
+            expected = [mcolors.to_hex(x) for x in expected_name]
             result = get_standard_colors(num_colors=num_colors)
             assert result == expected
 
@@ -138,8 +143,8 @@ def test_empty_color_raises(self, color):
     @pytest.mark.parametrize(
         "color",
         [
-            "BAD_COLOR",
-            ("red", "green", "BAD_COLOR"),
+            "bad_color",
+            ("red", "green", "bad_color"),
             (0.1,),
             (0.1, 0.2),
             (0.1, 0.2, 0.3, 0.4, 0.5),  # must be either 3 or 4 floats

From 76f76631b9814987482d9b2fe0150f2527e9d25b Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Sun, 18 Oct 2020 23:15:53 +0700
Subject: [PATCH 17/24] Remove test_style temporary

---
 pandas/tests/plotting/test_style.py | 155 ----------------------------
 1 file changed, 155 deletions(-)
 delete mode 100644 pandas/tests/plotting/test_style.py

diff --git a/pandas/tests/plotting/test_style.py b/pandas/tests/plotting/test_style.py
deleted file mode 100644
index 7fb041b44acb6..0000000000000
--- a/pandas/tests/plotting/test_style.py
+++ /dev/null
@@ -1,155 +0,0 @@
-from cycler import cycler
-import pytest
-
-from pandas import Series
-
-from pandas.plotting._matplotlib.style import get_standard_colors
-
-
-class TestGetStandardColors:
-    @pytest.mark.parametrize(
-        "num_colors, expected",
-        [
-            (3, ["red", "green", "blue"]),
-            (5, ["red", "green", "blue", "red", "green"]),
-            (7, ["red", "green", "blue", "red", "green", "blue", "red"]),
-            (2, ["red", "green"]),
-            (1, ["red"]),
-        ],
-    )
-    def test_default_colors_named_from_prop_cycle(self, num_colors, expected):
-        import matplotlib as mpl
-
-        mpl_params = {
-            "axes.prop_cycle": cycler(color=["red", "green", "blue"]),
-        }
-        with mpl.rc_context(rc=mpl_params):
-            result = get_standard_colors(num_colors=num_colors)
-            assert result == expected
-
-    @pytest.mark.parametrize(
-        "num_colors, expected",
-        [
-            (1, ["b"]),
-            (3, ["b", "g", "r"]),
-            (4, ["b", "g", "r", "y"]),
-            (5, ["b", "g", "r", "y", "b"]),
-            (7, ["b", "g", "r", "y", "b", "g", "r"]),
-        ],
-    )
-    def test_default_colors_named_from_prop_cycle_string(self, num_colors, expected):
-        import matplotlib as mpl
-
-        mpl_params = {
-            "axes.prop_cycle": cycler(color="bgry"),
-        }
-        with mpl.rc_context(rc=mpl_params):
-            result = get_standard_colors(num_colors=num_colors)
-            assert result == expected
-
-    @pytest.mark.parametrize(
-        "num_colors, expected_name",
-        [
-            (1, ["C0"]),
-            (3, ["C0", "C1", "C2"]),
-            (
-                12,
-                [
-                    "C0",
-                    "C1",
-                    "C2",
-                    "C3",
-                    "C4",
-                    "C5",
-                    "C6",
-                    "C7",
-                    "C8",
-                    "C9",
-                    "C0",
-                    "C1",
-                ],
-            ),
-        ],
-    )
-    def test_default_colors_named_undefined_prop_cycle(self, num_colors, expected_name):
-        import matplotlib as mpl
-        import matplotlib.colors as mcolors
-
-        with mpl.rc_context(rc={}):
-            expected = [mcolors.to_hex(x) for x in expected_name]
-            result = get_standard_colors(num_colors=num_colors)
-            assert result == expected
-
-    @pytest.mark.parametrize(
-        "num_colors, expected",
-        [
-            (1, ["red", "green", (0.1, 0.2, 0.3)]),
-            (2, ["red", "green", (0.1, 0.2, 0.3)]),
-            (3, ["red", "green", (0.1, 0.2, 0.3)]),
-            (4, ["red", "green", (0.1, 0.2, 0.3), "red"]),
-        ],
-    )
-    def test_user_input_color_sequence(self, num_colors, expected):
-        color = ["red", "green", (0.1, 0.2, 0.3)]
-        result = get_standard_colors(color=color, num_colors=num_colors)
-        assert result == expected
-
-    @pytest.mark.parametrize(
-        "num_colors, expected",
-        [
-            (1, ["r", "g", "b", "k"]),
-            (2, ["r", "g", "b", "k"]),
-            (3, ["r", "g", "b", "k"]),
-            (4, ["r", "g", "b", "k"]),
-            (5, ["r", "g", "b", "k", "r"]),
-            (6, ["r", "g", "b", "k", "r", "g"]),
-        ],
-    )
-    def test_user_input_color_string(self, num_colors, expected):
-        color = "rgbk"
-        result = get_standard_colors(color=color, num_colors=num_colors)
-        assert result == expected
-
-    @pytest.mark.parametrize(
-        "num_colors, expected",
-        [
-            (1, [(0.1, 0.2, 0.3)]),
-            (2, [(0.1, 0.2, 0.3), (0.1, 0.2, 0.3)]),
-            (3, [(0.1, 0.2, 0.3), (0.1, 0.2, 0.3), (0.1, 0.2, 0.3)]),
-        ],
-    )
-    def test_user_input_color_floats(self, num_colors, expected):
-        color = (0.1, 0.2, 0.3)
-        result = get_standard_colors(color=color, num_colors=num_colors)
-        assert result == expected
-
-    @pytest.mark.parametrize(
-        "color, num_colors, expected",
-        [
-            ("Crimson", 1, ["Crimson"]),
-            ("DodgerBlue", 2, ["DodgerBlue", "DodgerBlue"]),
-            ("firebrick", 3, ["firebrick", "firebrick", "firebrick"]),
-        ],
-    )
-    def test_user_input_named_color_string(self, color, num_colors, expected):
-        result = get_standard_colors(color=color, num_colors=num_colors)
-        assert result == expected
-
-    @pytest.mark.parametrize("color", ["", [], (), Series([], dtype="object")])
-    def test_empty_color_raises(self, color):
-        with pytest.raises(ValueError, match="Invalid color argument"):
-            get_standard_colors(color=color, num_colors=1)
-
-    @pytest.mark.parametrize(
-        "color",
-        [
-            "bad_color",
-            ("red", "green", "bad_color"),
-            (0.1,),
-            (0.1, 0.2),
-            (0.1, 0.2, 0.3, 0.4, 0.5),  # must be either 3 or 4 floats
-        ],
-    )
-    def test_bad_color_raises(self, color):
-        with pytest.raises(ValueError, match="Invalid color"):
-            get_standard_colors(color=color, num_colors=5)

From 0f0f4bc917d9630d7c37a05a7108c3c865e5b898 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Mon, 19 Oct 2020 00:29:44 +0700
Subject: [PATCH 18/24] BLD: remove cycler from dependencies temporary

---
 environment.yml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/environment.yml b/environment.yml
index 7efb12ffb6b19..77a9c5fd4822d 100644
--- a/environment.yml
+++ b/environment.yml
@@ -52,7 +52,6 @@ dependencies:
   - botocore>=1.11
   - hypothesis>=3.82
   - moto  # mock S3
-  - cycler  # test matplotlib colors cycle
   - flask
   - pytest>=5.0.1
   - pytest-cov

From b8daf79ac5b4b97f611f4d010644d6550bd270d2 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Mon, 19 Oct 2020 11:57:28 +0700
Subject: [PATCH 19/24] Revert "Remove test_style temporary"

This reverts commit 76f76631b9814987482d9b2fe0150f2527e9d25b.
---
 pandas/tests/plotting/test_style.py | 155 ++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)
 create mode 100644 pandas/tests/plotting/test_style.py

diff --git a/pandas/tests/plotting/test_style.py b/pandas/tests/plotting/test_style.py
new file mode 100644
index 0000000000000..7fb041b44acb6
--- /dev/null
+++ b/pandas/tests/plotting/test_style.py
@@ -0,0 +1,155 @@
+from cycler import cycler
+import pytest
+
+from pandas import Series
+
+from pandas.plotting._matplotlib.style import get_standard_colors
+
+
+class TestGetStandardColors:
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (3, ["red", "green", "blue"]),
+            (5, ["red", "green", "blue", "red", "green"]),
+            (7, ["red", "green", "blue", "red", "green", "blue", "red"]),
+            (2, ["red", "green"]),
+            (1, ["red"]),
+        ],
+    )
+    def test_default_colors_named_from_prop_cycle(self, num_colors, expected):
+        import matplotlib as mpl
+
+        mpl_params = {
+            "axes.prop_cycle": cycler(color=["red", "green", "blue"]),
+        }
+        with mpl.rc_context(rc=mpl_params):
+            result = get_standard_colors(num_colors=num_colors)
+            assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, ["b"]),
+            (3, ["b", "g", "r"]),
+            (4, ["b", "g", "r", "y"]),
+            (5, ["b", "g", "r", "y", "b"]),
+            (7, ["b", "g", "r", "y", "b", "g", "r"]),
+        ],
+    )
+    def test_default_colors_named_from_prop_cycle_string(self, num_colors, expected):
+        import matplotlib as mpl
+
+        mpl_params = {
+            "axes.prop_cycle": cycler(color="bgry"),
+        }
+        with mpl.rc_context(rc=mpl_params):
+            result = get_standard_colors(num_colors=num_colors)
+            assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected_name",
+        [
+            (1, ["C0"]),
+            (3, ["C0", "C1", "C2"]),
+            (
+                12,
+                [
+                    "C0",
+                    "C1",
+                    "C2",
+                    "C3",
+                    "C4",
+                    "C5",
+                    "C6",
+                    "C7",
+                    "C8",
+                    "C9",
+                    "C0",
+                    "C1",
+                ],
+            ),
+        ],
+    )
+    def test_default_colors_named_undefined_prop_cycle(self, num_colors, expected_name):
+        import matplotlib as mpl
+        import matplotlib.colors as mcolors
+
+        with mpl.rc_context(rc={}):
+            expected = [mcolors.to_hex(x) for x in expected_name]
+            result = get_standard_colors(num_colors=num_colors)
+            assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, ["red", "green", (0.1, 0.2, 0.3)]),
+            (2, ["red", "green", (0.1, 0.2, 0.3)]),
+            (3, ["red", "green", (0.1, 0.2, 0.3)]),
+            (4, ["red", "green", (0.1, 0.2, 0.3), "red"]),
+        ],
+    )
+    def test_user_input_color_sequence(self, num_colors, expected):
+        color = ["red", "green", (0.1, 0.2, 0.3)]
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, ["r", "g", "b", "k"]),
+            (2, ["r", "g", "b", "k"]),
+            (3, ["r", "g", "b", "k"]),
+            (4, ["r", "g", "b", "k"]),
+            (5, ["r", "g", "b", "k", "r"]),
+            (6, ["r", "g", "b", "k", "r", "g"]),
+        ],
+    )
+    def test_user_input_color_string(self, num_colors, expected):
+        color = "rgbk"
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize(
+        "num_colors, expected",
+        [
+            (1, [(0.1, 0.2, 0.3)]),
+            (2, [(0.1, 0.2, 0.3), (0.1, 0.2, 0.3)]),
+            (3, [(0.1, 0.2, 0.3), (0.1, 0.2, 0.3), (0.1, 0.2, 0.3)]),
+        ],
+    )
+    def test_user_input_color_floats(self, num_colors, expected):
+        color = (0.1, 0.2, 0.3)
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize(
+        "color, num_colors, expected",
+        [
+            ("Crimson", 1, ["Crimson"]),
+            ("DodgerBlue", 2, ["DodgerBlue", "DodgerBlue"]),
+            ("firebrick", 3, ["firebrick", "firebrick", "firebrick"]),
+        ],
+    )
+    def test_user_input_named_color_string(self, color, num_colors, expected):
+        result = get_standard_colors(color=color, num_colors=num_colors)
+        assert result == expected
+
+    @pytest.mark.parametrize("color", ["", [], (), Series([], dtype="object")])
+    def test_empty_color_raises(self, color):
+        with pytest.raises(ValueError, match="Invalid color argument"):
+            get_standard_colors(color=color, num_colors=1)
+
+    @pytest.mark.parametrize(
+        "color",
+        [
+            "bad_color",
+            ("red", "green", "bad_color"),
+            (0.1,),
+            (0.1, 0.2),
+            (0.1, 0.2, 0.3, 0.4, 0.5),  # must be either 3 or 4 floats
+        ],
+    )
+    def test_bad_color_raises(self, color):
+        with pytest.raises(ValueError, match="Invalid color"):
+            get_standard_colors(color=color, num_colors=5)

From 37734e847e2b68c3d86e9607e700e2a860277ad5 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Mon, 19 Oct 2020 12:18:53 +0700
Subject: [PATCH 20/24] REF: import cycler from matplotlib.pyplot

---
 pandas/tests/plotting/test_style.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/plotting/test_style.py b/pandas/tests/plotting/test_style.py
index 7fb041b44acb6..57cb7d7c6ba67 100644
--- a/pandas/tests/plotting/test_style.py
+++ b/pandas/tests/plotting/test_style.py
@@ -1,4 +1,3 @@
-from cycler import cycler
 import pytest
 
 from pandas import Series
@@ -19,6 +18,7 @@ class TestGetStandardColors:
     )
     def test_default_colors_named_from_prop_cycle(self, num_colors, expected):
         import matplotlib as mpl
+        from matplotlib.pyplot import cycler
 
         mpl_params = {
             "axes.prop_cycle": cycler(color=["red", "green", "blue"]),
@@ -39,6 +39,7 @@ def test_default_colors_named_from_prop_cycle(self, num_colors, expected):
     )
     def test_default_colors_named_from_prop_cycle_string(self, num_colors, expected):
         import matplotlib as mpl
+        from matplotlib.pyplot import cycler
 
         mpl_params = {
             "axes.prop_cycle": cycler(color="bgry"),

From 765836f3a7ae90c878b6044597a355b91d585fbc Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Mon, 19 Oct 2020 12:59:55 +0700
Subject: [PATCH 21/24] TST: mark test skip if no mpl

---
 pandas/tests/plotting/test_style.py | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/pandas/tests/plotting/test_style.py b/pandas/tests/plotting/test_style.py
index 57cb7d7c6ba67..d58983a2352da 100644
--- a/pandas/tests/plotting/test_style.py
+++ b/pandas/tests/plotting/test_style.py
@@ -1,10 +1,16 @@
+from contextlib import suppress
+
 import pytest
 
+import pandas.util._test_decorators as td
+
 from pandas import Series
 
-from pandas.plotting._matplotlib.style import get_standard_colors
+with suppress(ImportError):
+    from pandas.plotting._matplotlib.style import get_standard_colors
 
 
+@td.skip_if_no_mpl
 class TestGetStandardColors:
     @pytest.mark.parametrize(
         "num_colors, expected",

From f0ea70176ba7f78feadacb0fcba6f7ed96a1a47b Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Fri, 23 Oct 2020 23:32:55 +0700
Subject: [PATCH 22/24] REF: use pytest.importorskip

---
 pandas/tests/plotting/test_style.py | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/pandas/tests/plotting/test_style.py b/pandas/tests/plotting/test_style.py
index d58983a2352da..665bda15724fd 100644
--- a/pandas/tests/plotting/test_style.py
+++ b/pandas/tests/plotting/test_style.py
@@ -1,16 +1,11 @@
-from contextlib import suppress
-
 import pytest
 
-import pandas.util._test_decorators as td
-
 from pandas import Series
 
-with suppress(ImportError):
-    from pandas.plotting._matplotlib.style import get_standard_colors
+pytest.importorskip("matplotlib")
+from pandas.plotting._matplotlib.style import get_standard_colors
 
 
-@td.skip_if_no_mpl
 class TestGetStandardColors:
     @pytest.mark.parametrize(
         "num_colors, expected",

From dedd0dd266e5d25a289371a7273d2ce710e58cf1 Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Fri, 30 Oct 2020 15:35:01 +0700
Subject: [PATCH 23/24] REF: extract new method _is_single_color

1. Rename _is_single_color -> _is_single_string_color
2. Extract new method _is_single_color, which checks whether
the color provided is a single color, that can be either string
or a sequence of floats.
3. Allow integers to be a part of float sequence color,
(1, 0.4, 0.2, 0.5), for example.
---
 pandas/plotting/_matplotlib/style.py | 34 +++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index b8f162008f852..e5ede22ca7126 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -106,18 +106,36 @@ def _get_colors_from_color(
     if len(color) == 0:
         raise ValueError(f"Invalid color argument: {color}")
 
-    if isinstance(color, str) and _is_single_color(color):
-        # GH #36972
-        return [color]
-
-    if _is_floats_color(color):
-        color = cast(Sequence[float], color)
+    if _is_single_color(color):
+        color = cast(Color, color)
         return [color]
 
     color = cast(Collection[Color], color)
     return list(_gen_list_of_colors_from_iterable(color))
 
 
+def _is_single_color(color: Union[Color, Collection[Color]]) -> bool:
+    """Check if ``color`` is a single color, not a sequence of colors.
+
+    Single color is of these kinds:
+        - Named color "red"
+        - Alias "g"
+        - Sequence of floats, such as (0.1, 0.2, 0.3) or (0.1, 0.2, 0.3, 0.4).
+
+    See Also
+    --------
+    _is_single_string_color
+    """
+    if isinstance(color, str) and _is_single_string_color(color):
+        # GH #36972
+        return True
+
+    if _is_floats_color(color):
+        return True
+
+    return False
+
+
 def _gen_list_of_colors_from_iterable(color: Collection[Color]) -> Iterator[Color]:
     """
     Yield colors from string of several letters or from collection of colors.
@@ -134,7 +152,7 @@ def _is_floats_color(color: Union[Color, Collection[Color]]) -> bool:
     return bool(
         is_list_like(color)
         and (len(color) == 3 or len(color) == 4)
-        and all(isinstance(x, float) for x in color)
+        and all(isinstance(x, (int, float)) for x in color)
     )
 
 
@@ -168,7 +186,7 @@ def _random_color(column: int) -> List[float]:
     return rs.rand(3).tolist()
 
 
-def _is_single_color(color: Color) -> bool:
+def _is_single_string_color(color: Color) -> bool:
     """Check if ``color`` is a single color.
 
     Examples of single colors:

From b36983414ba8663173af4f421286d286737a4c0a Mon Sep 17 00:00:00 2001
From: Maxim Ivanov <ivanovmg@gmail.com>
Date: Tue, 3 Nov 2020 19:38:52 +0700
Subject: [PATCH 24/24] DOC: add/update docstrings

---
 pandas/plotting/_matplotlib/style.py | 83 ++++++++++++++++++++++++----
 1 file changed, 73 insertions(+), 10 deletions(-)

diff --git a/pandas/plotting/_matplotlib/style.py b/pandas/plotting/_matplotlib/style.py
index e5ede22ca7126..b2c7b2610845c 100644
--- a/pandas/plotting/_matplotlib/style.py
+++ b/pandas/plotting/_matplotlib/style.py
@@ -32,10 +32,42 @@ def get_standard_colors(
     color_type: str = "default",
     color: Optional[Union[Dict[str, Color], Color, Collection[Color]]] = None,
 ):
+    """
+    Get standard colors based on `colormap`, `color_type` or `color` inputs.
+
+    Parameters
+    ----------
+    num_colors : int
+        Minimum number of colors to be returned.
+        Ignored if `color` is a dictionary.
+    colormap : :py:class:`matplotlib.colors.Colormap`, optional
+        Matplotlib colormap.
+        When provided, the resulting colors will be derived from the colormap.
+    color_type : {"default", "random"}, optional
+        Type of colors to derive. Used if provided `color` and `colormap` are None.
+        Ignored if either `color` or `colormap` are not None.
+    color : dict or str or sequence, optional
+        Color(s) to be used for deriving sequence of colors.
+        Can be either be a dictionary, or a single color (single color string,
+        or sequence of floats representing a single color),
+        or a sequence of colors.
+
+    Returns
+    -------
+    dict or list
+        Standard colors. Can either be a mapping if `color` was a dictionary,
+        or a list of colors with a length of `num_colors` or more.
+
+    Warns
+    -----
+    UserWarning
+        If both `colormap` and `color` are provided.
+        Parameter `color` will override.
+    """
     if isinstance(color, dict):
         return color
 
-    colors = _get_colors(
+    colors = _derive_colors(
         color=color,
         colormap=colormap,
         color_type=color_type,
@@ -45,14 +77,45 @@ def get_standard_colors(
     return _cycle_colors(colors, num_colors=num_colors)
 
 
-def _get_colors(
+def _derive_colors(
     *,
     color: Optional[Union[Color, Collection[Color]]],
     colormap: Optional[Union[str, "Colormap"]],
     color_type: str,
     num_colors: int,
 ) -> List[Color]:
-    """Get colors from user input."""
+    """
+    Derive colors from either `colormap`, `color_type` or `color` inputs.
+
+    Get a list of colors either from `colormap`, or from `color`,
+    or from `color_type` (if both `colormap` and `color` are None).
+
+    Parameters
+    ----------
+    color : str or sequence, optional
+        Color(s) to be used for deriving sequence of colors.
+        Can be either be a single color (single color string, or sequence of floats
+        representing a single color), or a sequence of colors.
+    colormap : :py:class:`matplotlib.colors.Colormap`, optional
+        Matplotlib colormap.
+        When provided, the resulting colors will be derived from the colormap.
+    color_type : {"default", "random"}, optional
+        Type of colors to derive. Used if provided `color` and `colormap` are None.
+        Ignored if either `color` or `colormap`` are not None.
+    num_colors : int
+        Number of colors to be extracted.
+
+    Returns
+    -------
+    list
+        List of colors extracted.
+
+    Warns
+    -----
+    UserWarning
+        If both `colormap` and `color` are provided.
+        Parameter `color` will override.
+    """
     if color is None and colormap is not None:
         return _get_colors_from_colormap(colormap, num_colors=num_colors)
     elif color is not None:
@@ -115,10 +178,10 @@ def _get_colors_from_color(
 
 
 def _is_single_color(color: Union[Color, Collection[Color]]) -> bool:
-    """Check if ``color`` is a single color, not a sequence of colors.
+    """Check if `color` is a single color, not a sequence of colors.
 
     Single color is of these kinds:
-        - Named color "red"
+        - Named color "red", "C0", "firebrick"
         - Alias "g"
         - Sequence of floats, such as (0.1, 0.2, 0.3) or (0.1, 0.2, 0.3, 0.4).
 
@@ -167,7 +230,7 @@ def _get_colors_from_color_type(color_type: str, num_colors: int) -> List[Color]
 
 
 def _get_default_colors(num_colors: int) -> List[Color]:
-    """Get ``num_colors`` of default colors from matplotlib rc params."""
+    """Get `num_colors` of default colors from matplotlib rc params."""
     import matplotlib.pyplot as plt
 
     colors = [c["color"] for c in plt.rcParams["axes.prop_cycle"]]
@@ -175,7 +238,7 @@ def _get_default_colors(num_colors: int) -> List[Color]:
 
 
 def _get_random_colors(num_colors: int) -> List[Color]:
-    """Get ``num_colors`` of random colors."""
+    """Get `num_colors` of random colors."""
     return [_random_color(num) for num in range(num_colors)]
 
 
@@ -187,9 +250,9 @@ def _random_color(column: int) -> List[float]:
 
 
 def _is_single_string_color(color: Color) -> bool:
-    """Check if ``color`` is a single color.
+    """Check if `color` is a single string color.
 
-    Examples of single colors:
+    Examples of single string colors:
         - 'r'
         - 'g'
         - 'red'
@@ -205,7 +268,7 @@ def _is_single_string_color(color: Color) -> bool:
     Returns
     -------
     bool
-        True if ``color`` looks like a valid color.
+        True if `color` looks like a valid color.
         False otherwise.
     """
     conv = matplotlib.colors.ColorConverter()