Question

我有CSV数据文件，带有带时间戳记录的本地时间。遗憾的是，数据文件涵盖了夏令时变化的时期（2013年11月3日），因此记录时间戳的时间分量为：12:45, 1:00, 1:15, 1:30, 1:45, 1:00, 1:15, 1:30, 1:45, 2:00。我希望能够将数据库中的值转换并存储为UTC。

不幸的是.NET的标准DateTime.Parse()函数会解析为（2013年11月3日全部）：

| Time String | Parsed Local Time | In DST | Parsed Local Time to UTC
|  12:45 am   |    12:45 am       |   Yes  |     4:45 am
| 12:59:59 am |    12:59:59 am    |   Yes  |     4:59:59 am
|  01:00 am   |     1:00 am       |   No   |     6:00 am
|  01:15 am   |     1:15 am       |   No   |     6:15 am

因此它永远不会将1:00-1:59:59 am范围视为在DST中，并且我在UTC中解析的时间戳会跳一小时。

是否有一个库或类允许我解析时间戳并考虑DST的变化？就像一些可实例化的类，它会记住它已经收到的时间戳流并相应地调整解析的时间戳吗？

关于解析时可以进行的数据的假设：

我在本地和UTC文件的标题部分中有文件的开始时间（第一条记录的时间戳）。
记录按时间顺序排列
所有当地时间均为东部标准
数据也可能是另一种方式：从DST进入它
记录包含以下格式的完整时间戳：yyyy/mm/dd HH:mm:ss（2013/11/03 00:45:00）

注意：虽然我的软件是在C＃中，但我没有特别标记C＃/ .NET，因为我认为我可以使用任何语言实现解决方案并在必要时重新编码。

Answer 1

如果连续时间戳无法以UTC时间表示，那么此Python脚本可以将本地时间转换为UTC：

#!/usr/bin/env python3
import sys
from datetime import datetime, timedelta
import pytz  # $ pip install pytz

tz = pytz.timezone('America/New_York' if len(sys.argv) < 2 else sys.argv[1])
previous = None #XXX set it from UTC time: `first_entry_utc.astimezone(tz)`
for line in sys.stdin: # read from stdin
    naive = datetime.strptime(line.strip(), "%Y/%m/%d %H:%M:%S") # no timezone
    try:
        local = tz.localize(naive, is_dst=None) # attach timezone info
    except pytz.AmbiguousTimeError:
        # assume ambiguous time always corresponds to True -> False transition
        local = tz.localize(naive, is_dst=True)
        if previous >= local: # timestamps must be increasing
            local = tz.localize(naive, is_dst=False)
        assert previous < local
    #NOTE: allow NonExistentTimeError to propagate (there shouldn't be
    # invalid local times in the input)
    previous = local
    utc = local.astimezone(pytz.utc)
    timestamp = utc.timestamp()
    time_format = "%Y-%m-%d %H:%M:%S %Z%z"
    print("{local:{time_format}}; {utc:{time_format}}; {timestamp:.0f}"
          .format_map(vars()))

输入

2013/11/03 00:45:00
2013/11/03 01:00:00
2013/11/03 01:15:00
2013/11/03 01:30:00
2013/11/03 01:45:00
2013/11/03 01:00:00
2013/11/03 01:15:00
2013/11/03 01:30:00
2013/11/03 01:45:00
2013/11/03 02:00:00

输出

2013-11-03 00:45:00 EDT-0400; 2013-11-03 04:45:00 UTC+0000; 1383453900
2013-11-03 01:00:00 EDT-0400; 2013-11-03 05:00:00 UTC+0000; 1383454800
2013-11-03 01:15:00 EDT-0400; 2013-11-03 05:15:00 UTC+0000; 1383455700
2013-11-03 01:30:00 EDT-0400; 2013-11-03 05:30:00 UTC+0000; 1383456600
2013-11-03 01:45:00 EDT-0400; 2013-11-03 05:45:00 UTC+0000; 1383457500
2013-11-03 01:00:00 EST-0500; 2013-11-03 06:00:00 UTC+0000; 1383458400
2013-11-03 01:15:00 EST-0500; 2013-11-03 06:15:00 UTC+0000; 1383459300
2013-11-03 01:30:00 EST-0500; 2013-11-03 06:30:00 UTC+0000; 1383460200
2013-11-03 01:45:00 EST-0500; 2013-11-03 06:45:00 UTC+0000; 1383461100
2013-11-03 02:00:00 EST-0500; 2013-11-03 07:00:00 UTC+0000; 1383462000

Answer 2

在C＃中：

// Define the input values.
string[] input =
{
    "2013-11-03 00:45:00",
    "2013-11-03 01:00:00",
    "2013-11-03 01:15:00",
    "2013-11-03 01:30:00",
    "2013-11-03 01:45:00",
    "2013-11-03 01:00:00",
    "2013-11-03 01:15:00",
    "2013-11-03 01:30:00",
    "2013-11-03 01:45:00",
    "2013-11-03 02:00:00",
};

// Get the time zone the input is meant to be interpreted in.
TimeZoneInfo tz = TimeZoneInfo.FindSystemTimeZoneById("Eastern Standard Time");

// Create an array for the output values
DateTimeOffset[] output = new DateTimeOffset[input.Length];

// Start with the assumption that DST is active, as ambiguities occur when moving
// out of daylight time into standard time.
bool dst = true;

// Iterate through the input.
for (int i = 0; i < input.Length; i++)
{
    // Parse the input string as a DateTime with Unspecified kind
    DateTime dt = DateTime.ParseExact(input[i], "yyyy-MM-dd HH:mm:ss",
                                      CultureInfo.InvariantCulture);

    // Determine the offset.
    TimeSpan offset;
    if (tz.IsAmbiguousTime(dt))
    {
        // Get the possible offsets, and use the DST flag and the previous entry
        // to determine if we are past the transition point.  This only works
        // because we have outside knowledge that the items are in sequence.
        TimeSpan[] offsets = tz.GetAmbiguousTimeOffsets(dt);
        offset = dst && (i == 0 || dt >= output[i - 1].DateTime)
                 ? offsets[1] : offsets[0];
    }
    else
    {
        // The value is unambiguous, so just get the single offset it can be.
        offset = tz.GetUtcOffset(dt);
    }

    // Use the determined values to construct a DateTimeOffset
    DateTimeOffset dto = new DateTimeOffset(dt, offset);

    // We can unambiguously check a DateTimeOffset for daylight saving time,
    // which sets up the DST flag for the next iteration.
    dst = tz.IsDaylightSavingTime(dto);

    // Save the DateTimeOffset to the output array.
    output[i] = dto;
}


// Show the output for debugging
foreach (var dto in output)
{
    Console.WriteLine("{0:yyyy-MM-dd HH:mm:ss zzzz} => {1:yyyy-MM-dd HH:mm:ss} UTC",
                       dto, dto.UtcDateTime);
}

输出：

2013-11-03 00:45:00 -04:00 => 2013-11-03 04:45:00 UTC
2013-11-03 01:00:00 -04:00 => 2013-11-03 05:00:00 UTC
2013-11-03 01:15:00 -04:00 => 2013-11-03 05:15:00 UTC
2013-11-03 01:30:00 -04:00 => 2013-11-03 05:30:00 UTC
2013-11-03 01:45:00 -04:00 => 2013-11-03 05:45:00 UTC
2013-11-03 01:00:00 -05:00 => 2013-11-03 06:00:00 UTC
2013-11-03 01:15:00 -05:00 => 2013-11-03 06:15:00 UTC
2013-11-03 01:30:00 -05:00 => 2013-11-03 06:30:00 UTC
2013-11-03 01:45:00 -05:00 => 2013-11-03 06:45:00 UTC
2013-11-03 02:00:00 -05:00 => 2013-11-03 07:00:00 UTC

请注意，这假设您第一次遇到类似于1:00的模糊时间，它将在DST中。假设您的列表被截断为最后5个条目 - 您不会知道这些条目是在标准时间内。在那种特殊情况下，你无能为力。

在观察夏令时的同时解析本地时间（到UTC）中的有序时间戳

2 个答案:

输入

输出