[R] short-hand to avoid use of length() in subsetting vectors?

[Steve Lianoglou]

Hi,

On Tue, Jan 10, 2012 at 6:04 PM, Eric Rupley <erupley at umich.edu> wrote:
>
> Hi--
>
> I suspect this is a frequently considered (and possibly asked) question, but I haven't thus far found an answer:
>
>        For slicing a vector with x[…], is there a symbol for length(x)?
>
> I'm seeking a short-hand for referring to the length of vector one is trying to index.
>
> E.g., for a data.frame, say,
>
>> test.frame <-data.frame(matrix(c(1:100),ncol=10,nrow=10,byrow=T))
>> names(test.frame) <- names(islands)[1:10]
>
> is there a short-hand for subsetting
>
>> test.frame$Baffin[1:(length(test.frame$Baffin)-3)]
> [1]  6 16 26 36 46 56 66
>>
>>
>
> that would allow one to avoid the "(length(some.dataframe$variable)-offset)"?

Sadly there is no shorthand of the (exact) type you are looking for.

You can access the data like so, however:

R> head(test.frame$Baffin, -3)
[1]  6 16 26 36 46 56 66

I think that's as good as you're going to get, but let's see what
other suggestions pop up.

-steve

-- 
Steve Lianoglou
Graduate Student: Computational Systems Biology
 | Memorial Sloan-Kettering Cancer Center
 | Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact