Question

我创建了一个时间序列数据框，我将用它将其他时间序列数据合并到。

dates2010 <- seq(as.POSIXct("2010-06-15 00:00:00", tz = "GMT"), as.POSIXct("2010-09-15 23:00:00", tz = "GMT"), by="hour")  # make string of DateTimes for summer 2010
dates2011 <- seq(as.POSIXct("2011-06-15 00:00:00", tz = "GMT"), as.POSIXct("2011-09-15 23:00:00", tz = "GMT"), by="hour")  # make string of DateTimes for summer 2011
dates <- c(dates2010, dates2011)                           # combine the dates from both years
sites <- c("a", "b", "c")                                  # make string of all sites
datereps <- rep(dates, length(sites))                      # repeat the date string the same number of times as there are sites
sitereps <- rep(sites, each = length(dates))               # repeat each site in the string the same number of times as there are dates 
n <- data.frame(DateTime = datereps, SiteName = sitereps)  # merge two strings with all dates and all sites
n <- n[order(n$SiteName, n$Date),]                         # re-order based on site, then date

如果我运行上述代码，＆＃39; dates2010＆＃39;和＆＃39; dates2011＆＃39;采用GMT格式：dates2010[1]＆＃34; 2011-06-15 00:00:00 GMT＆＃34;。但是当我创建对象＆＃39; dates＆＃39;由于某种原因，格式切换到EST：dates[1] ＆＃34; 2010-06-14 19:00:00 EST＆＃34;

也许它与POSIX类有关？

class(dates2010)
[1] "POSIXct" "POSIXt"

我试图change the default time zone for R转到GMT以避免时区切换问题。当我尝试订购数据框时，这会导致NA错误错误。并将其他数据框合并到＆＃39; n＆＃39;。

n <- n[order(n$SiteName, n$Date),]
Warning message:
In xtfrm.POSIXct(x) : NAs introduced by coercion

有关如何保持时区不变并避免NA强制错误的任何想法？谢谢！

Answer 1

c()删除属性。因此，当您创建dates时，时区已被删除，并且它会自动默认为当前区域设置。幸运的是，您可以使用structure()并在那里设置时区。

dates <- structure(c(dates2010, dates2011), tzone = "GMT")
head(dates)
# [1] "2010-06-15 00:00:00 GMT" "2010-06-15 01:00:00 GMT" 
# [3] "2010-06-15 02:00:00 GMT" "2010-06-15 03:00:00 GMT"
# [5] "2010-06-15 04:00:00 GMT" "2010-06-15 05:00:00 GMT"

如果已创建dates，您可以稍后添加/更改tzone属性。

attr(dates, "tzone") <- "GMT"

如何使用POSIX DateTime维护时区并避免R中强制引入的NA？

1 个答案: