strptime返回NA

Question

I am getting NA value for my date string using strptime in R. I looked at the various answers, but it didn't work. Here is my code

startDate=strptime("Wed May 25 01:51:32 UTC 2016", format="%a %B %d %H:%m:%S %Z %Y", tz="UTC")
print(startDate)

Any help would be appreciated.

Answer 1

"%H:%m:%S" should be "%H:%M:%S" . Once you change that, you'll get an error because %Z is not valid for input.

If all the datetime strings have UTC timezone, this will work:

R> strptime("Wed May 25 01:51:32 UTC 2016", "%a %B %d %H:%M:%S UTC %Y", "UTC")
[1] "2016-05-25 01:51:32 UTC"

If not, then you can extract the year and prepend it to the string, because strptime will ignore all characters after those specified by the format string.

R> dts <- "Wed May 25 01:51:32 UTC 2016"
R> dtf <- "%Y %a %B %d %H:%M:%S"
R> strptime(paste(substring(dts, nchar(dts)-3), dts), dtf, "UTC")
[1] "2016-05-25 01:51:32 UTC"