apply POSIXct to a data frame

Question

I have a data frame named df like that

 id          time
 1        1392825600
 2        1392825597
 3        1392825587

where is time the time in seconds since epoch at UTC (the local time of the data is the Hong Kong timezone)

I would like to put this into a standard time stamp using POSIXct

For example

> test = as.POSIXct(1392825587, origin="1970-01-01", tz = "Hongkong")
> test
 [1] "2014-02-19 23:59:47 HKT"

But when I want to apply that to my data frame, here is what i get:

df$TimeStamp = as.POSIXct(df$time, origin="1970-01-01", tz = "Hongkong")
 id          time        TimeStamp
 1        1392825600   2014-02-19 23:00:00
 2        1392825597   2014-02-19 22:59:57
 3        1392825587   2014-02-19 22:59:47

Everything have a lag of 1hour and it looks like the time zone used was my computer's one rather than the HK one (my time zone as 1 hour difference with HK)

I cannot replicate your results. It looks like a bug/typo in your code (`df$time` is not the same as `dft$time`). — Joshua Ulrich, Aug 10 '14 at 12:59

score 0 · Answer 1 · answered Aug 10 '14 at 19:38

0

Try this:

format(as.POSIXct(df$time, origin="1970-01-01", tz = "UTC"),
       tz="Asia/Hong_Kong", usetz=TRUE)

answered Aug 10 '14 at 19:38

Matt Johnson-Pint

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apply POSIXct to a data frame

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