R as.POSIXct 解析错误

发布于 2024-10-22 19:13:50 字数 502 浏览 1 评论 0原文

我正在尝试解析时间字符串向量并遇到一个奇怪的错误。例如，如果我运行以下代码部分，R 将按预期返回结果。

time_format="%m/%d/%Y %H:%M:%S"
t_1 = "03/13/2011 01:00:10"
as.POSIXct(t_1, format = time_format)

输出：

[1] "2011-03-13 01:00:10 EST"

但是，如果我将时间稍微更改为凌晨 2 点，

t_2 = "03/13/2011 02:00:10"
as.POSIXct(t_2, format = time_format)

输出将变为：

[1] NA

我可以在 Windows 7 和 XP 上的 R 2.11.1 和 2.12.2 上重现它。有人遇到同样的问题吗？

谢谢，德里克

原文

I am trying to parse a vector of time string and came across a strange error. For example, if I run the following section of code, R returned the result as expected.

time_format="%m/%d/%Y %H:%M:%S"
t_1 = "03/13/2011 01:00:10"
as.POSIXct(t_1, format = time_format)

Output:

[1] "2011-03-13 01:00:10 EST"

However, if I change the time slightly to 2 AM

t_2 = "03/13/2011 02:00:10"
as.POSIXct(t_2, format = time_format)

The output became:

[1] NA

I can reproduce it on R 2.11.1 and 2.12.2 on Windows 7 and XP. Does anyone encounter the same problem?

Thanks,
Derek

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冰之心 2024-10-29 19:13:50

您无法解析不存在的时间。 02:00:10 不存在，因为我们在本周六晚上/周日早上切换到夏令时，“向前迈进”。 R 知道这一点：

R> t_1 = "03/13/2011 01:00:10"; as.POSIXct(t_1, format = time_format)
[1] "2011-03-13 01:00:10 CST"
R> t_2 = "03/13/2011 02:00:10"; as.POSIXct(t_2, format = time_format)
[1] "2011-03-13 01:00:10 CST"
R> t_3 = "03/13/2011 03:00:10"; as.POSIXct(t_3, format = time_format)
[1] "2011-03-13 03:00:10 CDT"
R>

在 Linux 上，我的时区库似乎可以应付——减去一小时后，02:00:10 变成 01:00:10。

You cannot parse non-existing times. 02:00:10 did not exist as we had 'spring forward' this Saturday night / Sunday morning with the switch to daylight-savings. R knows this:

R> t_1 = "03/13/2011 01:00:10"; as.POSIXct(t_1, format = time_format)
[1] "2011-03-13 01:00:10 CST"
R> t_2 = "03/13/2011 02:00:10"; as.POSIXct(t_2, format = time_format)
[1] "2011-03-13 01:00:10 CST"
R> t_3 = "03/13/2011 03:00:10"; as.POSIXct(t_3, format = time_format)
[1] "2011-03-13 03:00:10 CDT"
R>

On Linux, my timezone library seems to cope -- 02:00:10 becomes 01:00:10 as an hour is subtracted.

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