Bert Gunter gunter.berton at gene.com
Fri Sep 26 02:04:31 CEST 2014

```Inline.

-- Bert

Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
Clifford Stoll

On Thu, Sep 25, 2014 at 3:28 PM, Sven E. Templer <sven.templer at gmail.com> wrote:
> see inline for another vectorized example.

Nope. x-apply family functions are disguised (Interpreter level, not C
level) loops. Rarely more efficient than for() loops, but often
clearer and more convenient.

Cheers,
Bert

>
> On 25 September 2014 23:05, David L Carlson <dcarlson at tamu.edu> wrote:
>> Another approach
>>
>> fun <- function(i, dat=x) {
>>      grp <- rep(1:(nrow(dat)/i), each=i)
>>      aggregate(dat[1:length(grp),]~grp, FUN=sum)
>> }
>>
>> lapply(2:6, fun, dat=TT)
>>
>>
>> -------------------------------------
>> David L Carlson
>> Department of Anthropology
>> Texas A&M University
>> College Station, TX 77840-4352
>>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Rui Barradas
>> Sent: Thursday, September 25, 2014 3:34 PM
>> To: eliza botto; r-help at r-project.org
>> Subject: Re: [R] adding rows
>>
>> Hello,
>>
>> Try the following.
>>
>> fun <- function(x, r){
>>         if(r > 0){
>>                 m <- length(x) %/% r
>>                 y <- numeric(m)
>>                 for(i in seq_len(m)){
>>                         y[i] <- sum(x[((i - 1)*r + 1):(i*r)])
>>                 }
>>                 y
>>         }else{
>>                 NULL
>>         }
>> }
>
>
>
> fun <- function(x,r) {
>   i <- length(x)%/%r
>   tapply(x[1:(i*r)], gl(i,r), sum)
> }
>
>
>
>>
>> apply(TT, 2, fun, r = 2)
>> apply(TT, 2, fun, r = 3)
>> etc
>>
>>
>> Hope this helps,
>>
>>
>>
>> Em 25-09-2014 20:50, eliza botto escreveu:
>>> Dear useRs,
>>> Here is my data with two columns and 20 rows.
>>>> dput(TT)
>>> structure(c(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240, 264, 288, 312, 336, 360, 384, 408, 432, 456, 480), .Dim = c(20L, 2L), .Dimnames = list(NULL, c("", "SS")))
>>> I first of all want to sum up continuously  two rows (1 & 2, 3 & 4, 5 & 6 and so on) of each column.
>>> Then I want to sum up 3 rows as (1-2-3,4-5-6,..... 16-17-18) and since 19th and 20th rows do not up 3 rows, so they should be ignored.
>>> Similarly with 4 sets of rows and 5 sets of rows and even 6.
>>> I hope I was clear.
>>> Thankyou so very much in advance,
>>> Eliza
>>>       [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>> ______________________________________________
>> R-help at r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> and provide commented, minimal, self-contained, reproducible code.
>>
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