C++：Vector 計算 均值(mean) 和 方差(variance)

vector<>類型的數組, 計算均值和方差的最簡方法.

代碼:

double sum = std::accumulate(std::begin(resultSet), std::end(resultSet), 0.0);  
double mean =  sum / resultSet.size(); //均值  
     
double accum  = 0.0;  
std::for_each (std::begin(resultSet), std::end(resultSet), [&](const double d) {  
    accum  += (d-mean)*(d-mean);  
});  
     
double stdev = sqrt(accum/(resultSet.size()-1)); //方差

作者：csdn博客 Spike_King