[R] how to convert character string with only month and year into date

[David Winsemius]

On Sep 22, 2009, at 3:03 PM, Sean Zhang wrote:

> Dear R helpers.
>
> I am new to plotting time data using R.
> wonder how to convert character time info into date in R.
> I searched over the web but did not find answer.
>
> the input character string is something like 03_1993 or 03-1993, so  
> the
> precision is at month level.  I tried the following but failed.
> #R code below.
>
> strptime(c("03_1993"),"%m_%Y")
> strptime(c("03-1993"),"%m-%Y")
>
> Can you someone kindly show me to do it?
>

The usual R classes do not have a year-month version but package zoo  
does:

 > library(zoo)
 > as.yearmon("03_1993","%m_%Y")
[1] "Mar 1993"
>
--

David Winsemius, MD
Heritage Laboratories
West Hartford, CT