Try this:
mydat[order(as.Date(mydat$date, "%m/%d/%Y"), decreasing = TRUE),]
On Thu, Dec 30, 2010 at 9:27 AM, Vincy Pyne <vincy_p...@yahoo.ca> wrote:
> Dear 'HTH' R friends
>
> I have a small dataframe as given below. I need to sort this database based
> on date in a decending order. I am not sure whether I have defined the date
> column in a proper format.
>
> mydat<-data.frame(date = (c("1/31/2010", "2/28/2010", "3/31/2010",
> "4/30/2010", "5/31/2010", "6/30/2010", "7/31/2010", "8/31/2010",
> "9/30/2010", "10/31/2010", "11/30/2010", "12/28/2010")), total=c(429, 25,
> 239, 99, 100, 96, 18, 21, 10, 76, 101, 81), newspapers=c(103, 4, 37, 109,
> 52, 87, 17, 13, 10, 56, 87, 14))
>
>
> > mydat
> date total newspapers
> 1 1/31/2010 429 103
> 2 2/28/2010 25 4
> 3 3/31/2010 239 37
> 4 4/30/2010 99 109
> 5 5/31/2010 100 52
> 6 6/30/2010 96 87
> 7 7/31/2010 18 17
> 8 8/31/2010 21 13
> 9 9/30/2010 10 10
> 10 10/31/2010 76 56
> 11 11/30/2010 101 87
> 12 12/28/2010 81 14
>
> I need to sort this data in a DESCENDING order based on a date. I.e. I need
> to have
>
> date total newspapers
> 12/28/2010 81 14
> 11/30/2010 101 87
> 10/31/2010 76 56
> .................................
> ..................................
>
> 1/31/2010 429 103
>
> When I tried
>
> mydat.sort <- mydat[order(mydat$date)]
>
> > mydat.sort <- mydat[order(mydat$date)]
>
> Error in `[.data.frame`(mydat, order(mydat$date)) : undefined columns
> selected
>
> Kindly guide
>
> Vincy Pyne
>
>
>
>
> [[alternative HTML version deleted]]
>
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
>
--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O
[[alternative HTML version deleted]]
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