Reading timestamp data in R from multiple time zones

Question

I have a column of time stamps in character format that looks like this:

2015-09-24 06:00:00 UTC

2015-09-24 05:00:00 UTC

dateTimeZone <- c         


        

Answer 1

You can get there by checking each row and processing accordingly, and then putting everything back into a consistent UTC time. (#edited to now include matching the timezone abbreviations to the full timezone specification)

dates <- c(
  "2015-09-24 06:00:00 UTC",
  "2015-09-24 05:00:00 PDT"
)

#extract timezone from dates
datestz <- vapply(strsplit(dates," "), tail, 1, FUN.VALUE="")

## Make a master list of abbreviation to 
## full timezone names. Used an arbitrary summer
## and winter date to try to catch daylight savings timezones.

tzabbrev <- vapply(
  OlsonNames(),
  function(x) c(
    format(as.POSIXct("2000-01-01",tz=x),"%Z"),
    format(as.POSIXct("2000-07-01",tz=x),"%Z")
  ),
  FUN.VALUE=character(2)
)
tmp <- data.frame(Olson=OlsonNames(), t(tzabbrev), stringsAsFactors=FALSE)
final <- unique(data.frame(tmp[1], abbrev=unlist(tmp[-1])))

## Do the matching:
out <- Map(as.POSIXct, dates, tz=final$Olson[match(datestz,final$abbrev)])
as.POSIXct(unlist(out), origin="1970-01-01", tz="UTC")
#  2015-09-24 06:00:00 UTC   2015-09-24 05:00:00 PDT 
#"2015-09-24 06:00:00 GMT" "2015-09-24 12:00:00 GMT"