静态面板回归模型——变系数回归 C++代码
时间: 2023-09-24 20:12:57 浏览: 42
下面是基于最小二乘法的变系数回归的 C++ 代码实现:
```cpp
#include <iostream>
#include <vector>
#include <cmath>
using namespace std;
// 变系数回归模型
class Regressor {
public:
Regressor(vector<double>& x, vector<double>& y) : x(x), y(y) {}
// 拟合模型
void fit() {
int n = x.size();
double S_xy = 0.0, S_xx = 0.0, S_y = 0.0, S_x = 0.0;
for (int i = 0; i < n; i++) {
S_xy += x[i] * y[i];
S_xx += x[i] * x[i];
S_y += y[i];
S_x += x[i];
}
double b = (n * S_xy - S_x * S_y) / (n * S_xx - S_x * S_x);
double a = (S_y - b * S_x) / n;
this->a = a;
this->b = b;
}
// 预测
double predict(double x) {
return a + b * x;
}
private:
vector<double> x, y;
double a, b;
};
int main() {
vector<double> x = {1, 2, 3, 4, 5};
vector<double> y = {2, 4, 5, 4, 5};
Regressor regressor(x, y);
regressor.fit();
cout << "模型参数:a = " << regressor.predict(0) << ", b = " << regressor.predict(1) << endl;
return 0;
}
```
这里使用的是最小二乘法来拟合模型,具体实现如下:
设 $y = a + bx$,则有:
$$
b = \frac{n\sum_{i=1}^{n}x_iy_i - \sum_{i=1}^{n}x_i\sum_{i=1}^{n}y_i}{n\sum_{i=1}^{n}x_i^2 - (\sum_{i=1}^{n}x_i)^2}
$$
$$
a = \frac{\sum_{i=1}^{n}y_i - b\sum_{i=1}^{n}x_i}{n}
$$
其中,$n$ 表示样本数量,$x_i$ 和 $y_i$ 分别表示第 $i$ 个样本的自变量和因变量。