我在尝试规范化和更新权重时收到运行时警告

Question

我试图在粒子过滤器中计算某些粒子的权重，然后相应地规范化这些权重。我的代码：

def update(particles, weights, landmark, sigma):
    n = 0.0
    for i in range(len(weights)):
        distance = np.power((particles[i][0] - landmark[0]) ** 2 + (particles[i][1] - 
        landmark[1])**2, 0.5)
        likelihood = exp(-(np.power(distance, 2))/2 * sigma ** 2)
        weights[i] = weights[i] * likelihood
        n += weights[i]
        weights += 1.e-30
        if n != 0:
            weights = weights / n

但是，我得到了一个错误： /Users/scottdayton/pycharm项目/不确定性研究/particle.py:30:RuntimeWarning:true_divide中遇到溢出 重量=重量/n /Users/scottdayton/pycharm项目/不确定性研究/particle.py:30:RuntimeWarning:在真除法中遇到无效值 重量=重量/n

Answer 1

正如在评论中所说，我在代码中添加了括号，但可能还有另一件事。我觉得你是在尝试将权重与可能性相乘，然后将结果标准化。为此，应将循环切割为2：

• 修正权重和总和
• 将标准化归纳为一

我会这样写：

def update(particles, weights, landmark, sigma):
    n = 0.0
    # Correction of weights and computation of the sum
    for i in range(len(weights)):
        distance = np.power((particles[i][0] - landmark[0]) ** 2 + (particles[i][1] - 
        landmark[1])**2, 0.5)
        likelihood = np.exp(-(np.power(distance, 2))/(2 * sigma ** 2))
        weights[i] = weights[i] * likelihood + 1.e-30
        n += weights[i]
    # Normalization to sum up to one
    for i in range(len(weights)):
        weights[i] = weights[i] / n