R supports date and time data differently than does SAS software. In SAS software, variables that represent dates or times are assigned a format such as DATE9. or TIME5. In R, classes are used to represent dates and times.
When a variable in a SAS data set is transferred to R software, the variable’s format is examined and the following occurs:
If the format is in the family of date formats (for example, DATEw.d), the variable in R is assigned the "Date" class.
If the format is in the family of datetime formats (for example, DATETIMEw.d) or time formats (for example, TIMEw.d), the variable in R is assigned the "POSIXct" and "POSIXt" classes.
In all other cases, the variable in R is assigned the "numeric" class.
When a variable in an R data frame is transferred to SAS software, the variable’s class is examined and the following occurs:
If the variable’s class is "Date," the corresponding SAS variable is assigned the DATE9. format.
If the variable’s class is "POSIXt," the corresponding SAS variable is assigned the DATETIME19. format.
In all other cases, the SAS variable is not assigned a format.