小程序搜集箱：散点多阶拟合（python）

小程序介绍：散点多阶拟合。

#! /usr/bin/env python
# -*- coding: utf-8 -*-

"""
This program is debugged by Harden Qiu
"""

import numpy as np
import matplotlib.pyplot as plt

x = np.array([-4,-3,-2,-1,0,1,2,3,4,5,6,7,8,9,10])
# y = np.array(2*(x**4) + x**2 + 9*x + 2) #假设因变量y刚好符合该公式
y = np.array([300,500,0,-10,0,20,200,300,1000,800,4000,5000,10000,9000,22000])

# coef 为系数，poly_fit 拟合函数
coef1 = np.polyfit(x,y, 1)
poly_fit1 = np.poly1d(coef1)
plt.plot(x, poly_fit1(x), 'g',label="1st-order fitting")
print(poly_fit1)

coef2 = np.polyfit(x,y, 2)
poly_fit2 = np.poly1d(coef2)
plt.plot(x, poly_fit2(x), 'b',label="2nd-order fitting")
print(poly_fit2)

coef3 = np.polyfit(x,y, 3)
poly_fit3 = np.poly1d(coef3)
plt.plot(x, poly_fit3(x), 'y',label="3rd-order fitting")
print(poly_fit3)

plt.scatter(x, y, color='black')
plt.legend(loc=2)
plt.show()

运行得到：