[R] from 3 numeric variables to a string

[Marc Schwartz]

On Jun 5, 2009, at 3:56 PM, Marc Belisle wrote:

> Hi there,
>
> I have 3 numeric variables: day (e.g., 05), month (e.g., 06), year  
> (e.g.,
> 2009).
>
> I would like to create a (string) variable of the following form:
> month/day/year (e.g., 06/05/2009).
>
> I would be grateful to anyone who could point me toward a solution.
>
> Sincerely,
>
> Marc

If you want the result just as text:

day <- 5
month <- 6
year <- 2009

 > sprintf("%02d/%02d/%4d", day, month, year)
[1] "05/06/2009"


Note that the day/month integers will of course not have the leading  
zeros, so using sprintf() allows you to specify that the results  
should include them (the '%02d' in the format string).

See ?sprintf for more information.

If you further want to use them as actual date objects, you can use  
as.Date() on the result:

 > as.Date(sprintf("%02d/%02d/%4d", day, month, year), format = "%d/%m/ 
%Y")
[1] "2009-06-05"

Note that the above is now of Class 'Date':

 > str(as.Date(sprintf("%02d/%02d/%4d", day, month, year), format =  
"%d/%m/%Y"))
Class 'Date'  num 14400

which then enables you to perform date based operations on the results.

See ?as.Date for more information on converting text to dates.

HTH,

Marc Schwartz