R help - Apr 2008 - Avoiding a loop

Dear R-users,

I've been working with three different data sets (X, Y and Z) with the same
dimension (i.e, n \times k). What I needed to do was to conform a 4th data
set, i.e. FINAL, which first row was the X's first row, its second row was
the Y's first row, and its third row was the Z's first row, and so on.

My code is below. Is it possible to avoid the loop?

Thanks in advance,

Jorge



# ----- Code starts here

# Seed and data frames X, Y and Z
set.seed(123)
X=matrix(rnorm(300),ncol=5)
Y=matrix(rpois(300,10),ncol=5)
Z=matrix(rexp(300,1),ncol=5)

# First five columns and rows
X[1:3,1:5]
Y[1:3,1:5]
Z[1:3,1:5]

# FINAL' six rows
res=NULL; for(i in 1:nrow(X)) res=rbind(res,X[i,],Y[i,],Z[i,])
FINAL=data.frame(from.data=c('X','Y','Z'),res)
FINAL[1:9,1:6]

# ----- Code ends here

	[[alternative HTML version deleted]]

Will this do it for you:

# Seed and data frames X, Y and Z
set.seed(123)
X=matrix(rnorm(300),ncol=5)
Y=matrix(rpois(300,10),ncol=5)
Z=matrix(rexp(300,1),ncol=5)

index <- seq(1, by=3, length=nrow(X))
FINAL <- matrix(ncol=5, nrow=3*nrow(X))
FINAL[index,] <- X
FINAL[index + 1,] <- Y
FINAL[index + 2,] <- Z


On Mon, Apr 21, 2008 at 11:44 AM, Jorge Ivan Velez
<jorgeivanvelez at gmail.com> wrote:
> Dear R-users,
>
> I've been working with three different data sets (X, Y and Z) with the
same
> dimension (i.e, n \times k). What I needed to do was to conform a 4th data
> set, i.e. FINAL, which first row was the X's first row, its second row
was
> the Y's first row, and its third row was the Z's first row, and so
on.
>
> My code is below. Is it possible to avoid the loop?
>
> Thanks in advance,
>
> Jorge
>
>
>
> # ----- Code starts here
>
> # Seed and data frames X, Y and Z
> set.seed(123)
> X=matrix(rnorm(300),ncol=5)
> Y=matrix(rpois(300,10),ncol=5)
> Z=matrix(rexp(300,1),ncol=5)
>
> # First five columns and rows
> X[1:3,1:5]
> Y[1:3,1:5]
> Z[1:3,1:5]
>
> # FINAL' six rows
> res=NULL; for(i in 1:nrow(X)) res=rbind(res,X[i,],Y[i,],Z[i,])
> FINAL=data.frame(from.data=c('X','Y','Z'),res)
> FINAL[1:9,1:6]
>
> # ----- Code ends here
>
>        [[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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?