# -*- coding:utf-8 -*-
import numpy as np
import matplotlib.pyplot as plt
from scipy.interpolate import interp1d
plt.rcParams['savefig.dpi'] = 300 # 图片像素
plt.rcParams["savefig.format"] = 'pdf' # 保存为pdf LaTex排版使用
plt.rcParams['savefig.bbox'] = 'tight' # 图片白边变窄
# 准备画图
fig = plt.figure()
ax = fig.add_subplot(111)
# 准备数据
data1 = [[4/3,3],[2,2],[3.5,4/3.5]]
data2 = [[2,3.5],[2.5,2.6],[4.2,2.1]]
# 插值
xx,yy = zip(*data1)
f = interp1d(xx,yy,kind='quadratic')
x = np.linspace(min(xx),max(xx),100)
y = f(x)
# 画线 参数与matlab类似
l1, = ax.plot(x,y,'r-',linewidth=2)
x,y = zip(*data1)
l2, = ax.plot(x,y,'rs')
x,y = zip(*data2)
l3, = ax.plot(x,y,'o')
# 标注
# \sigma
x,y = zip(data1[0],data2[0])
# plt.plot(x,y,'-',c='gray')
plt.annotate(s="", xy=data1[0],