python用matplotlib绘制二维坐标轴,设置箭头指向,文本内容方式

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(-10, 10, 100)
y1 = 2 * x
y2 = x * x
plt.figure()
plt.xlabel('X axis')
plt.ylabel('Y axis')
plt.plot(x, y1, linestyle='--')
plt.plot(x, y2)
plt.show()

ax = plt.gca()  # 获取整张图像的坐标的对象

# 将右边，上边的两条边颜色设置为空 其实就相当于抹掉这两条边
ax.spines[‘right'].set_color(‘none')
ax.spines[‘top'].set_color(‘none')

ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')

# 设置（0，0）为两坐标轴的交点
ax.spines[‘bottom'].set_position((‘data', 0))
ax.spines[‘left'].set_position((‘data', 0))

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(-10, 10, 100)
y1 = 2 * x
y2 = x * x
plt.figure()
plt.xlabel('X axis')
plt.ylabel('Y axis')  # 设置坐标轴的文字标签
ax = plt.gca()  # get current axis 获得坐标轴对象
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')  # 将右边 上边的两条边颜色设置为空 其实就相当于抹掉这两条边
ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')  # 指定下边的边作为 x 轴   指定左边的边为 y 轴
ax.spines['bottom'].set_position(('data', 0))  # 指定 data  设置的bottom(也就是指定的x轴)绑定到y轴的0这个点上
ax.spines['left'].set_position(('data', 0))
plt.plot(x, y1, linestyle='--')
plt.plot(x, y2)
plt.show()

annotate(s='str', xy=(x,y), xycoords='data', xytext=(l1,l2), textcoords, arrowprops)
# s为标注内容
# xy为基准点
# xycoords='data' xy的坐标是基于data的
# xytext 为注释文字的坐标位置
# textcoords='offset point'代表以这个点为基准
# arrowprops描述箭头，线的弧度等信息，箭头参数,参数类型为字典dict

# 添加标注
x0 = 1
y0 = 2 * x0 + 1
plt.scatter(x0, y0, s=50, color='b') 
plt.plot([x0, x0], [y0, y0], 'k--', lw=2.5)
plt.annotate(r'$2x+1=%s$' % y0, xy=(x0, y0), xycoords='data', xytext=(+30, -30),
             textcoords='offset points', fontsize=16,
             arrowprops=dict(arrowstyle='->', connectionstyle='arc3,rad=.2'))

import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(-3, 3, 50)
y = 2*x+1
plt.figure(num=1, figsize=(8, 5))
plt.plot(x, y)
ax = plt.gca()
ax.spines['right'].set_color('none')
ax.spines['top'].set_color('none')
ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')
ax.spines['bottom'].set_position(('data', 0))
ax.spines['left'].set_position(('data', 0))
# 添加标注
x0 = 1
y0 = 2 * x0 + 1
plt.scatter(x0, y0, s=50, color='b')
plt.plot([x0, x0], [y0, y0], 'k--', lw=2.5)
plt.annotate(r'$2x+1=%s$' % y0, xy=(x0, y0), xycoords='data', xytext=(+30, -30),
             textcoords='offset points', fontsize=16,
             arrowprops=dict(arrowstyle='->', connectionstyle='arc3,rad=.2'))
plt.show()

plt.text(x, y, s)
# x,y为文字位置
# s为文字内容

plt.text(-3.7, 3, r'$This\ is\ the\ some\ text.\ \mu\ \sigma_i\ \alpha_t$',
         fontdict={'size': 16, 'color': 'r'})