python分段多项式拟合

对于Python中的分段多项式拟合，你可以使用numpy和scipy库来实现。下面是一个简单的示例代码：

import numpy as np
from scipy.optimize import curve_fit

# 定义分段多项式函数
def piecewise_polynomial(x, *params):
    result = np.zeros_like(x)
    for i in range(0, len(params), 3):
        mask = np.logical_and(x >= params[i], x < params[i+1])
        result[mask] = params[i+2] * (x[mask] - params[i]) ** 2 + params[i+2]
    return result

# 定义拟合数据
x_data = np.array([1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
y_data = np.array([1, 4, 9, 16, 25, 36, 49, 64, 81, 100])

# 定义初始参数猜测值
initial_params = [1, 3, 1, 5, 7, 2]

# 进行拟合
fit_params, _ = curve_fit(piecewise_polynomial, x_data, y_data, p0=initial_params)

# 输出拟合的参数
print("拟合参数:", fit_params)

# 测试拟合结果
x_test = np.linspace(1, 10, 100)
y_test = piecewise_polynomial(x_test, *fit_params)

# 输出拟合结果
print("拟合结果:", y_test)