问题
I have a SAS dataset containing a datetime variable. I have ported this dataset into R using the sas7bdat package but the datetime variable is shown in integer number format (e.g. 1706835972). Is there any way to convert this integer into a date format?
回答1:
To match exactly what SAS outputs for default datetime structure, you need to use as.POSIXct as was mentioned in comments, and additionally use the tz=UTC argument:
sasDateTimes <- c(1706835972, 1716835972, 1726835972, 1736835972, 1746835972,
1756835972, 1766835972, 1776835972, 1786835972, 1796835972, 1806835972,
1816835972, 1826835972, 1836835972, 1846835972, 1856835972, 1866835972,
1876835972, 1886835972, 1896835972, 1906835972, 1916835972, 1926835972,
1936835972, 1946835972, 1956835972, 1966835972, 1976835972, 1986835972,
1996835972)
rPOSIX <- as.POSIXct(sasDateTimes,origin='1960-01-01',tz="UTC")
rPOSIX
[1] "2014-02-01 01:06:12 UTC" "2014-05-27 18:52:52 UTC" "2014-09-20 12:39:32 UTC" "2015-01-14 06:26:12 UTC" "2015-05-10 00:12:52 UTC" "2015-09-02 17:59:32 UTC"
[7] "2015-12-27 11:46:12 UTC" "2016-04-21 05:32:52 UTC" "2016-08-14 23:19:32 UTC" "2016-12-08 17:06:12 UTC" "2017-04-03 10:52:52 UTC" "2017-07-28 04:39:32 UTC"
[13] "2017-11-20 22:26:12 UTC" "2018-03-16 16:12:52 UTC" "2018-07-10 09:59:32 UTC" "2018-11-03 03:46:12 UTC" "2019-02-26 21:32:52 UTC" "2019-06-22 15:19:32 UTC"
[19] "2019-10-16 09:06:12 UTC" "2020-02-09 02:52:52 UTC" "2020-06-03 20:39:32 UTC" "2020-09-27 14:26:12 UTC" "2021-01-21 08:12:52 UTC" "2021-05-17 01:59:32 UTC"
[25] "2021-09-09 19:46:12 UTC" "2022-01-03 13:32:52 UTC" "2022-04-29 07:19:32 UTC" "2022-08-23 01:06:12 UTC" "2022-12-16 18:52:52 UTC" "2023-04-11 12:39:32 UTC"
Those will perfectly match what SAS displays in the default format (DATETIME17.). Output from SAS:
x=1706835972, Formatted: 01FEB14:01:06:12
x=1716835972, Formatted: 27MAY14:18:52:52
x=1726835972, Formatted: 20SEP14:12:39:32
x=1736835972, Formatted: 14JAN15:06:26:12
x=1746835972, Formatted: 10MAY15:00:12:52
x=1756835972, Formatted: 02SEP15:17:59:32
x=1766835972, Formatted: 27DEC15:11:46:12
x=1776835972, Formatted: 21APR16:05:32:52
x=1786835972, Formatted: 14AUG16:23:19:32
x=1796835972, Formatted: 08DEC16:17:06:12
x=1806835972, Formatted: 03APR17:10:52:52
x=1816835972, Formatted: 28JUL17:04:39:32
x=1826835972, Formatted: 20NOV17:22:26:12
x=1836835972, Formatted: 16MAR18:16:12:52
x=1846835972, Formatted: 10JUL18:09:59:32
x=1856835972, Formatted: 03NOV18:03:46:12
x=1866835972, Formatted: 26FEB19:21:32:52
x=1876835972, Formatted: 22JUN19:15:19:32
x=1886835972, Formatted: 16OCT19:09:06:12
x=1896835972, Formatted: 09FEB20:02:52:52
x=1906835972, Formatted: 03JUN20:20:39:32
x=1916835972, Formatted: 27SEP20:14:26:12
x=1926835972, Formatted: 21JAN21:08:12:52
x=1936835972, Formatted: 17MAY21:01:59:32
x=1946835972, Formatted: 09SEP21:19:46:12
x=1956835972, Formatted: 03JAN22:13:32:52
x=1966835972, Formatted: 29APR22:07:19:32
x=1976835972, Formatted: 23AUG22:01:06:12
x=1986835972, Formatted: 16DEC22:18:52:52
x=1996835972, Formatted: 11APR23:12:39:32
If the data was entered with time zone corrections into SAS, you should leave out the tz argument. In my experience, however, SAS datetimes usually are not stored respective to a particular timezone. Whether they are or not is not normally stored as part of the dataset, unfortunately; you might be able to look at the format that was used on the dataset (if it is one of the timezone displaying formats, odds are it does include timezones), but even that is not a guarantee. You would have to verify with the data source whether the datetimes are relative to local datetime (ie, # of seconds from 1/1/1960 local time midnight, or # of seconds from 1/1/1960 UTC midnight).
来源：https://stackoverflow.com/questions/24413673/sas-datetime-to-r-date-format