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Create a regular sequence of date-times (POSIXct) using seq()

Asked 2012-01-19T10:03:38.730
23

My goal is to create a vector of POSIXct time stamps given a start, an end and a delta (15min, 1hour, 1day). I hoped I could use seq for this, but I have a problem converting between the numeric and POSIXct representation:

now <- Sys.time()
now
# [1] "2012-01-19 10:30:39 CET"
as.POSIXct(as.double(now), origin="1970-01-01", tz="CET")
# [1] "2012-01-19 09:30:39 CET"
as.POSIXct(as.double(now), origin=as.POSIXct("1970-01-01", tz="CET"), tz="CET")
# [1] "2012-01-19 09:30:39 CET"

One hour gets lost during this conversion. What am I doing wrong?

r date posixct
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1 Answer

9

These time zone issues are always fiddly, but I think the problem is that your origin is being calculated in the wrong time zone (since the string only specifies the date).

Try using origin <- now - as.numeric(now).

Alternatively, use lubridate::origin, which is the string "1970-01-01 UTC".

A full solution, again using lubridate.

start <- now()
seq(start, start + days(3), by = "15 min")
answered 2012-01-19T10:45:50.207

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