[R] Extracting day of month from Date objects

Kang Min ngokangmin at gmail.com
Tue May 24 19:42:24 CEST 2011


Thanks Phil, chron is good.

On May 25, 1:34 am, Phil Spector <spec... at stat.berkeley.edu> wrote:
> I've always found the chron library to be useful for
> tasks like this:
>
> > x <- round(runif(10)*100000, digits=0)
> > y <- as.Date(x, origin="1970-01-01")
> > library(chron)
> > days(y)
>
>   [1] 7  25 26 25 10 24 1  31 12 8
> 31 Levels: 1 < 2 < 3 < 4 < 5 < 6 < 7 < 8 < 9 < 10 < 11 < 12 < 13 < ... < 31
>
> Notice that it returns the days as factors.
>
>                                         - Phil Spector
>                                          Statistical Computing Facility
>                                          Department of Statistics
>                                          UC Berkeley
>
> On May 24, 2011, at 10:19 AM, Kang Min wrote:
>
> > I have another question -
>
> > I'd like to extract dates from a vector of yyyy-mm-dd, so I just want
> > the dd.
>
> > x <- round(runif(10)*100000, digits=0)
> > y <- as.Date(x, origin="1970-01-01")
>
> > I tried this based on the code that Jim provided, but it just printed
> > the whole date. I think I just need to tweak it a little, but haven't
> > been able to figure it out.
>
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