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• Artists

• BBox

由于蓝线和红线的存在，现在刻度标注很难看清楚。我们可以使他们更大，也可以使它们的属性以便使得线呈现半透明的白色背景。这样做我们既可以看到数据也可以看到刻度标注了。

相关的设置代码：

...

for label in ax.get_xticklabels() + ax.get_yticklabels():

    label.set_fontsize(16)

    label.set_bbox(dict(facecolor='white', edgecolor='None', alpha=0.65))

...

设置前图像：

设置后图像：

完整的代码如下：

import numpy as np

import matplotlib.pyplot as plt

plt.figure(figsize=(8, 5), dpi=80)

plt.subplot(111)

X = np.linspace(-np.pi, np.pi, 256, endpoint=True)

C, S = np.cos(X), np.sin(X)

plt.plot(X, C, color="blue", linewidth=2.5, linestyle="-", label="cosine")

plt.plot(X, S, color="red", linewidth=2.5, linestyle="-",  label="sine")

ax = plt.gca()

ax.spines['right'].set_color('none')

ax.spines['top'].set_color('none')

ax.xaxis.set_ticks_position('bottom')

ax.spines['bottom'].set_position(('data', 0))

ax.yaxis.set_ticks_position('left')

ax.spines['left'].set_position(('data', 0))

plt.xlim(X.min() * 1.1, X.max() * 1.1)

plt.xticks([-np.pi, -np.pi / 2, 0, np.pi / 2, np.pi],

          [r'$-\pi$', r'$-\pi/2$', r'$0$', r'$+\pi/2$', r'$+\pi$'])

plt.ylim(C.min() * 1.1, C.max() * 1.1)

plt.yticks([-1, 1],

          [r'$-1$', r'$+1$'])

plt.legend(loc='upper left')

t = 2*np.pi/3

plt.plot([t, t], [0, np.cos(t)],

        color='blue', linewidth=1.5, linestyle="--")

plt.scatter([t, ], [np.cos(t), ], 50, color='blue')

plt.annotate(r'$sin(\frac{2\pi}{3})=\frac{\sqrt{3}}{2}$',

            xy=(t, np.sin(t)), xycoords='data',

            xytext=(10, 30), textcoords='offset points', fontsize=16,

            arrowprops=dict(arrowstyle="->", connectionstyle="arc3,rad=.2"))

plt.plot([t, t], [0, np.sin(t)],

        color='red', linewidth=1.5, linestyle="--")

plt.scatter([t, ], [np.sin(t), ], 50, color ='red')

plt.annotate(r'$cos(\frac{2\pi}{3})=-\frac{1}{2}$', xy=(t, np.cos(t)),

            xycoords='data', xytext=(-90, -50),

            textcoords='offset points', fontsize=16,

            arrowprops=dict(arrowstyle="->", connectionstyle="arc3,rad=.2"))

for label in ax.get_xticklabels() + ax.get_yticklabels():

    label.set_fontsize(16)

    label.set_bbox(dict(facecolor='white', edgecolor='None', alpha=0.65 ))

plt.show()