R help - Jan 2009 - finding row and column indices of date in multiple columns of a data frame

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

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
>
> ______________________________________________
> 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.
>
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