subsets problem

you can try

lapply(lapply(uniques, function(x) subset(df, date == x)), myfun)

or possibly more accurate (subset may be finicky due to scoping):

lapply(lapply(uniques, function(x) df[df$date == x, ]), myfun)

or use ?split

lapply(split(df, df$date), myfun)

HTH,

--sundar

Help with this much appreciated



I have a large dataframe that I would like to subset where the constraint



Test1 <- subset(df, date == uniques[[1]]), where uniques is a list of dates
that must be matched to create Test1.



I would like to perform an operation on Test1 that results in a single
column of data. So far so good.



How do loop through all values in the uniques list (say there is 50),
perform an operationon Test1,,,,Test50, and then bolt all the lists together
in a single list please ?



Regards





Glenn




       [[alternative HTML version deleted]]

______________________________________________
R-help at 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.

See if this illustration using the %in% operator within subset() is  
helpful:

 > df1 <- data.frame(x=1:10, y=sample(c("a","b","c"), 10,  
replace=TRUE)  )
 > uniques <- list("a","b")
 >
 > Test1 <- subset(df1, y %in% uniques)
 > Test1
   x y
1 1 b
4 4 a
5 5 b
6 6 b
7 7 a
9 9 a

Next question of course is whether you were using the word "list" in  
an r-specific fashion? Fortunately, I think %in% will also work with  
vector input.

You might not want to make 50 Test<n>'s. That would be very much  
against the spirit of R. Provide a simpler example involving 3 or 4  
lists and someone might step up and solve it. Of course, I may have  
given you a one step solution if you were thinking that uniques[[1]]  
was a single number.

Might be best to name your dataframe something other than df which is  
also valid function name for the density of the F distribution.

David Winsemius

On Feb 8, 2009, at 8:00 PM, glenn wrote:

> Help with this much appreciated
>
>
>
> I have a large dataframe that I would like to subset where the  
> constraint
>
>
>
> Test1 <- subset(df, date == uniques[[1]]), where uniques is a list  
> of dates
> that must be matched to create Test1.
>
>
>
> I would like to perform an operation on Test1 that results in a single
> column of data. So far so good.
>
>
>
> How do loop through all values in the uniques list (say there is 50),
> perform an operationon Test1,,,,Test50, and then bolt all the lists  
> together
> in a single list please ?
>
>
>
> Regards
>
>
>
>
>
> Glenn
>
>
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.