[R] Extracting Current and Old Date

[David Winsemius]

On Jul 28, 2013, at 12:20 PM, Peter Maclean wrote:

> #This my look trivial but has been killing my time
> #I want to extract most current and old date from mydates #variable that has more than 10,000 observation. 
> #Get days
> # use as.Date( ) to convert strings to dates 
> mydates <- as.Date(c("2007-06-22", "2007-05-21", "2004-04-13", "2004-03-11","2004-02-13",))
> #Is there a way/fuction to extract mostcurrent date
> #from mydates variable
> mostcurrent <- as.Date(c("2007-06-22"))
> 
> #Is there a way/function to extract olddate 
> #from mydates variable
> olddate    <- as.Date(c("2004-02-13"))
> 
> #Days between most current and old dayte
> days <- as.numeric(mostcurrent - olddate)  

The usual ways to work with numeric data have been given .Date methods:

> mydates <- as.Date(c("2007-06-22", "2007-05-21", "2004-04-13", "2004-03-11","2004-02-13"))
> min(mydates)
[1] "2004-02-13"
> max(mydates)
[1] "2007-06-22"
> range(mydates)
[1] "2004-02-13" "2007-06-22"
> diff(range(mydates))
Time difference of 1225 days

-- 

David Winsemius
Alameda, CA, USA