c++ - Boost::posix_time::ptime舍入到给定的分钟数

Question

我想将分钟数舍入到给定的步骤(15分钟)。像这样

"2002-01-20 23:35:59.000" -> "2002-01-20 23:30:00.000" 
"2002-01-20 23:00:59.000" -> "2002-01-20 23:00:00.000" 
"2002-01-20 23:10:59.000" -> "2002-01-20 23:15:00.000"
"2002-01-20 23:55:59.000" -> "2002-02-21 00:00:00.000"  

有增强功能吗？否则，是否有实现的方法？

Answer 1

您可以执行以下操作将整数舍入为一个整数

n = (n % period) * n;

要使它从半个周期开始舍入，只需将其抵消:

n = ((n + period/2) % period) * n;

现在，使用time_duration代替。遗憾的是，我们无法直接使用time_duration来执行/或%，因此我们将首先转换为秒:

ptime round_to(ptime t, time_duration period = boost::posix_time::minutes(15)) {
    auto units = (t.time_of_day() + period/2).total_seconds() / period.total_seconds();
    return { t.date(), period*units };
}

看到它 Live on Coliru

#include <boost/date_time.hpp>
using boost::posix_time::ptime;
using boost::posix_time::time_duration;

ptime round_to(ptime t, time_duration period = boost::posix_time::minutes(15)) {
    auto units = (t.time_of_day() + period/2).total_seconds() / period.total_seconds();
    return { t.date(), period*units };
}

int main() {
    for (auto period : std::vector<time_duration> {
            boost::posix_time::minutes(15),
            boost::posix_time::minutes(1),
            boost::posix_time::hours(1) })
    {
        std::cout << "-- Rounding to " << period << "\n";
        for (auto timestamp: {
                "2002-01-20 23:35:59.000",
                "2002-01-20 23:00:59.000",
                "2002-01-20 23:10:59.000",
                "2002-01-20 23:55:59.000",
            })
        {
            ptime input = boost::posix_time::time_from_string(timestamp);
            std::cout << input << " -> " << round_to(input, period) << "\n";
        }
    }
}

版画

-- Rounding to 00:15:00
2002-Jan-20 23:35:59 -> 2002-Jan-20 23:30:00
2002-Jan-20 23:00:59 -> 2002-Jan-20 23:00:00
2002-Jan-20 23:10:59 -> 2002-Jan-20 23:15:00
2002-Jan-20 23:55:59 -> 2002-Jan-21 00:00:00
-- Rounding to 00:01:00
2002-Jan-20 23:35:59 -> 2002-Jan-20 23:36:00
2002-Jan-20 23:00:59 -> 2002-Jan-20 23:01:00
2002-Jan-20 23:10:59 -> 2002-Jan-20 23:11:00
2002-Jan-20 23:55:59 -> 2002-Jan-20 23:56:00
-- Rounding to 01:00:00
2002-Jan-20 23:35:59 -> 2002-Jan-21 00:00:00
2002-Jan-20 23:00:59 -> 2002-Jan-20 23:00:00
2002-Jan-20 23:10:59 -> 2002-Jan-20 23:00:00
2002-Jan-20 23:55:59 -> 2002-Jan-21 00:00:00