Dear Gonçalo,

If DF is your data set, something like this should do the job:

which(DF==yourdate,arr.ind=TRUE)


> # Example
> Dates<-c('01/18/2009','01/19/2009','01/20/2009','01/21/2009')
> DF<-data.frame(
+        Site=sample(4),
+       "Site#"=sample(4),
+         Season=sample(4),
+        Day1=sample(Dates),
+         Day2= sample(Dates),
+          Day3=sample(Dates)
+      )
> DF
  Site Site. Season       Day1       Day2       Day3
1    2     3      1 01/21/2009 01/19/2009 01/19/2009
2    3     1      4 01/19/2009 01/18/2009 01/20/2009
3    1     2      2 01/20/2009 01/21/2009 01/18/2009
4    4     4      3 01/18/2009 01/20/2009 01/21/2009
> which(DF=='01/21/2009',arr.ind=TRUE)
     row col
[1,]   1   4
[2,]   3   5
[3,]   4   6


See ?which for more information.

HTH,

Jorge


On Wed, Jan 21, 2009 at 3:30 PM, Gonçalo Ferraz <gferraz29@gmail.com> wrote:

> Hi,
>
> I have a data.frame SAMPLES with columns:
>
> Site      Site#   Season   Day1   Day2   Day3
>
> Day1, Day2, Day3 are class "Date", the other columns are numeric or factor.
>
> I have a date "mydate" that may or may not be listed in my data.frame and I
> need to find that out.
> If "mydate" is there, I want to get the number of the data.frame row where
> it occurs.
>
> "mydate" may be in any of the three date columns and if it is there, it
> appears only once.
>
> Thank you for any advice and sorry if this is ni FAQ's - I couldn't find
> it.
>
> Gonzalo
>
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>

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