[R] subsets problem

[David Winsemius]

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]]
>
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