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1 | 1 | """ |
2 | 2 | ***************** |
3 | | -Specifying Colors |
| 3 | +Specifying colors |
4 | 4 | ***************** |
5 | 5 |
|
| 6 | +Color formats |
| 7 | +============= |
| 8 | +
|
6 | 9 | Matplotlib recognizes the following formats to specify a color. |
7 | 10 |
|
8 | 11 | +--------------------------------------+--------------------------------------+ |
|
74 | 77 | "Red", "Green", and "Blue" are the intensities of those colors. In combination, |
75 | 78 | they represent the colorspace. |
76 | 79 |
|
77 | | -Matplotlib draws Artists based on the ``zorder`` parameter. If there are no |
78 | | -specified values, Matplotlib defaults to the order of the Artists added to the |
79 | | -Axes. |
80 | | -
|
81 | | -The alpha for an Artist controls opacity. It indicates how the RGB color of the |
82 | | -new Artist combines with RGB colors already on the Axes. |
83 | | -
|
84 | | -The two Artists combine with alpha compositing. Matplotlib uses the equation |
85 | | -below to compute the result of blending a new Artist. |
| 80 | +Transparency |
| 81 | +============ |
86 | 82 |
|
87 | | -:: |
| 83 | +The *alpha* value of a color specifies its transparency, where 0 is fully |
| 84 | +transparent and 1 is fully opaque. When a color is semi-transparent, the |
| 85 | +background color will show through (see also :doc:`/gallery/misc/zorder_demo` |
| 86 | +to learn more about the drawing order). |
88 | 87 |
|
89 | | - RGB_{new} = RGB_{below} * (1 - \\alpha) + RGB_{artist} * \\alpha |
| 88 | +The *alpha* value determines the resulting color by blending the |
| 89 | +foreground color with the background color according to the formula |
90 | 90 |
|
91 | | -Alpha of 1 indicates the new Artist completely covers the previous color. |
92 | | -Alpha of 0 for top color is not visible; however, it contributes to blending |
93 | | -for intermediate values as the cumulative result of all previous Artists. The |
94 | | -following table contains examples. |
| 91 | +.. math:: |
95 | 92 |
|
96 | | -+---------------+-------------------------------------------------------------+ |
97 | | -| Alpha value | Visual | |
98 | | -+===============+=============================================================+ |
99 | | -| ``0.3`` | .. image:: ../../_static/color_zorder_A.png | |
100 | | -+---------------+-------------------------------------------------------------+ |
101 | | -| ``1`` | .. image:: ../../_static/color_zorder_B.png | |
102 | | -+---------------+-------------------------------------------------------------+ |
| 93 | + RGB_{result} = RGB_{background} * (1 - \\alpha) + RGB_{foreground} * \\alpha |
103 | 94 |
|
104 | | -.. note:: |
105 | | -
|
106 | | - Changing the order of Artists will generally change the resulting figure. |
| 95 | +Obviously, the resulting color depends on the draw order of the artists: |
| 96 | +""" |
107 | 97 |
|
| 98 | +import matplotlib.pyplot as plt |
| 99 | +from matplotlib.patches import Rectangle |
| 100 | + |
| 101 | +fig, ax = plt.subplots() |
| 102 | +ax.add_patch(Rectangle((0.08, 0.3), 0.4, 0.6, color='b', zorder=1, alpha=0.8)) |
| 103 | +ax.add_patch(Rectangle((0.3, 0.1), 0.4, 0.6, color='r', zorder=2, alpha=0.8)) |
| 104 | +ax.add_patch(Rectangle((0.52, 0.3), 0.4, 0.6, color='b', zorder=3, alpha=0.8)) |
| 105 | +ax.text(0.29, 0.8, "zorder=1", ha='center', color='white') |
| 106 | +ax.text(0.5, 0.2, "zorder=2", ha='center', color='white') |
| 107 | +ax.text(0.71, 0.8, "zorder=3", ha='center', color='white') |
| 108 | +ax.set_title('alpha=0.8') |
| 109 | +ax.axis('off') |
108 | 110 |
|
109 | | -"CN" color selection |
110 | | --------------------- |
111 | 111 |
|
112 | | -Matplotlib converts "CN" colors to RGBA when drawing Artists. The |
113 | | -:doc:`/tutorials/intermediate/color_cycle` section contains additional |
114 | | -information about controlling colors and style properties. |
115 | | -""" |
| 112 | +############################################################################### |
| 113 | +# "CN" color selection |
| 114 | +# ==================== |
| 115 | +# |
| 116 | +# Matplotlib converts "CN" colors to RGBA when drawing Artists. The |
| 117 | +# :doc:`/tutorials/intermediate/color_cycle` section contains additional |
| 118 | +# information about controlling colors and style properties. |
116 | 119 |
|
117 | 120 |
|
118 | 121 | import numpy as np |
@@ -144,7 +147,7 @@ def demo(sty): |
144 | 147 | # .. _xkcd-colors: |
145 | 148 | # |
146 | 149 | # Comparison between X11/CSS4 and xkcd colors |
147 | | -# ------------------------------------------- |
| 150 | +# =========================================== |
148 | 151 | # |
149 | 152 | # The xkcd colors come from a `user survey conducted by the webcomic xkcd |
150 | 153 | # <https://blog.xkcd.com/2010/05/03/color-survey-results/>`__. |
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