[R] Sorting a vector by date

[Laurent Faisnel]

Michael Kirschbaum wrote:
> Hello out there....
> 
> Again I have a problem and I stuck...
> 
> How can  I sort a vector of dates?

A look at ?sort could help...

> 
> For example I have the vector
> 
> a<-ISOdate(2001, 1, 1) + 70*86400*runif(10)
> 
> How can this vector be sorted chronological?

  a is :
  [1] "2001-03-05 10:48:42 CET" "2001-01-30 09:29:32 CET"
  [3] "2001-02-12 11:15:02 CET" "2001-03-07 23:58:43 CET"
  [5] "2001-01-16 08:02:11 CET" "2001-02-25 00:52:20 CET"
  [7] "2001-01-04 21:34:45 CET" "2001-01-30 09:37:40 CET"
  [9] "2001-02-05 19:10:17 CET" "2001-01-09 17:41:49 CET"

sort(a) does just what you wanted without any option - I still advise 
you to have a close look at ?sort


> And what's the function I should work with to handle  these entries?
> (in sense of:  which(a>2001-01-04) or somehting like that)

You have to convert with ISOdate the date you want to compare with the 
ones in the vector. For example,

d<-ISOdate(2001,2,1)

then you can do things like :

aa<-a[a<d]

See ?ISOdate

> 
> Thank you for helping
> 
> M.Kirschbaum
> 
> 	[[alternative HTML version deleted]]

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