c++ - 使用空的 boost::accumulators

Question

如何检查一个空的 boost::accumulators acc 与否？

例如:

if (acc.isEmpty())//I don't know what function here
 return 0;
else 
 return boost::accumulators::mean(acc).

因为如果它是空的，我得到 NaN for boost::accumulators::mean(acc)。

Answer 1

您可以使用累加器 count :

if (boost::accumulators::count(acc) == 0)//I don't know what function here
 return 0;
else 
 return boost::accumulators::mean(acc);

或者，您可以通过调用 std::isnan 来简单地检查它是否为 nan :

 if(std::isnan(boost::accumulators::mean(acc))
    return 0;
 else
    return boost::accumulators::mean(acc);