[R] handle date variables

[Yu-Ling Wu]

Thanks! This is helpful.

Three more questions. 
1. How to convert a string into a numeric value. For
example, convert '20010122' to 20010122.

2. How to convert a string into a date value. For
example, convert 20010122
to 2001 Jan 22, and get its day of the week, i.e.
Monday?

3. How to handle date variables in a loop? How to make
the following codes work? And how users should pass
the date arguments to the function?

fun1 <- function(firstdate, lastdate) {
      for ( i in firstdate:lastdate) {
         do something....
      }
}

fun1(2001/01/22, 2001/01/27)


--- Douglas Bates <bates at stat.wisc.edu> wrote:
> Yu-Ling Wu <yuling5 at yahoo.com> writes:
> 
> > I'd like to pass a string to a function as the
> value
> > of the argument.
> > Here is my code. However, it doesn't work. Please
> help
> > me with this.
> > 
> > Thanks,
> > Yu-Ling Wu
> >
>
-----------------------------------------------------
> > library(RODBC)
> > odbcConnect("console") -> myConnect
> > 
> > fun1 <- function(dd1) {
> > h3 <- sqlQuery(myConnect, "select * from console
> where
> > byday = 'dd1'group by by hour")
> > }
> 
> Use paste to construct a string from multiple input
> strings.
> 
> sqlQuery(myConnect,
>          paste("select * from console where byday
> =",
>                dd1, "group by hour"))


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