How to transform the date format as "20050425"

On Mon, 2005-04-25 at 15:18 -0500, Yong Wang wrote:

Dear R user,
if the dates are in format as "20050425" i.e., Apr. 25 2004"
can you suggest an easy way to transfom it to standard form
as "2005-04-25" or "2004Apr25" or "2005/04/25" or any other
format which is R recognizable?
if there is no easy way to do that, can you let me know what
is the function in R performing similiar function as the "string"
function in C or some other more basic language, so I can loop
through all dates to make the desired change. thank you regards

If you are just formatting the Date (ie. no time component) then look
at ?as.Date, which has a format argument:

as.Date("20050425", "%Y%M%d")

[1] "2005-04-25"

Using the format argument, you then return a standard Date class
object for use in R. The format argument varies as required for your
data format.

On the output side, there is the format() function, which has a method
for Dates, that you can then use to convert the Date class object into
a character vector:

MyDate <- as.Date("20050425", "%Y%M%d")
MyDate

[1] "2005-04-25"

format(MyDate, "%B %d %Y")

[1] "April 25 2005"

Also see ?strftime for details on date format strings.

HTH,

Marc Schwartz