直线或曲线拟合

 

代码实现：

import numpy as np

import matplotlib.pyplot as plt

from scipy import optimize

#直线方程函数

def f_1(x, A, B):

    return A*x + B

#二次曲线方程

def f_2(x, A, B, C):

    return A*x*x + B*x + C

#三次曲线方程

def f_3(x, A, B, C, D):

    return A*x*x*x + B*x*x + C*x + D

def plot_test():

    plt.figure()

    #拟合点

    x0 = [1, 2, 3, 4, 5]

    y0 = [1, 3, 8, 18, 36]

    #绘制散点

    plt.scatter(x0[:], y0[:], 25, "red")

    #直线拟合与绘制

    A1, B1 = optimize.curve_fit(f_1, x0, y0)[0]

    x1 = np.arange(0, 6, 0.01)

    y1 = A1*x1 + B1

    plt.plot(x1, y1, "blue")

    #二次曲线拟合与绘制

    A2, B2, C2 = optimize.curve_fit(f_2, x0, y0)[0]

    x2 = np.arange(0, 6, 0.01)

    y2 = A2*x2*x2 + B2*x2 + C2

    plt.plot(x2, y2, "green")

    #三次曲线拟合与绘制

    A3, B3, C3, D3= optimize.curve_fit(f_3, x0, y0)[0]

    x3 = np.arange(0, 6, 0.01)

    y3 = A3*x3*x3*x3 + B3*x3*x3 + C3*x3 + D3

    plt.plot(x3, y3, "purple")

    plt.title("test")

    plt.xlabel('x')

    plt.ylabel('y')

    plt.show()

    return