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I'm working with a date format of YYYY-mm-ddTHH:MM:SS.000Z (2014-02-05T08:45:01.326Z) or that has a separator T that separates the date from the time, and time indicator Z or "Zulu time" (UTC). I'm trying to store the timestamp as a class POSIXct using the following function:
timestamp <- as.POSIXct(strptime(as.character(data$Time), tz = "UTC", "%Y-%m-%d %H:%M:%S"))
at the moment I'm getting NA's. If anyone has some advice on how I can incorporate the 'T' and 'Z' indicators in my conversion I will highly appreciate it.
753
asked Feb 25 '14 09:02
You can use the as. Date( ) function to convert character data to dates. The format is as. Date(x, "format"), where x is the character data and format gives the appropriate format.
POSIXct stores date and time in seconds with the number of seconds beginning at 1 January 1970. Negative numbers are used to store dates prior to 1970. Thus, the POSIXct format stores each date and time a single value in units of seconds. Storing the data this way, optimizes use in data.
Time and Date Variables. The POSIXct data type is the number of seconds since the start of January 1, 1970. Negative numbers represent the number of seconds before this time, and positive numbers represent the number of seconds afterwards.
There are two POSIX date/time classes, which differ in the way that the values are stored internally. The POSIXct class stores date/time values as the number of seconds since January 1, 1970, while the POSIXlt class stores them as a list with elements for second, minute, hour, day, month, and year, among others.
You can include the characters in your format string:
d <- "2014-02-05T08:45:01.326Z"
timestamp <- strptime(d, tz = "UTC", "%Y-%m-%dT%H:%M:%OSZ")
Note that here %OS is used instead of %S because you have fractional seconds.
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