R help - Sep 2014 - adding rows

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]]

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
	}
}

apply(TT, 2, fun, r = 2)
apply(TT, 2, fun, r = 3)
etc


Hope this helps,

Rui Barradas


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
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>