Change from date and hour format to numeric format

Question

I am working in R and I need to change from a column in format

9/27/2011  3:33:00 PM 

to a value format. In Excel I can use the function <

Answer 1

This was useful for me:

> test=as.POSIXlt("09/13/2006", format="%m/%d/%Y")
> test
[1] "2006-09-13"
> 1900+test$year
[1] 2006
> test$yday
[1] 255
> test$yday/365
[1] 0.6986301
> 1900+test$year+test$yday/366
[1] 2006.697

You can use similar approaches if you need day numbers like in Excel.