R help - Jun 2006 - how to put the results of loop into a dataframe

Dear friends,
 suppose i want to do the following caulation for 100 times, how to put the
results of x , y and z into the same dataframe/dataset?
x<-runif(1)
y<-x+1
z<-x+y

thanks in advance!
-- 
Kind Regards,
Zhi Jie,Zhang ,PHD
Department of Epidemiology
School of Public Health
Fudan University
Tel:86-21-54237149

	[[alternative HTML version deleted]]

Dear friends,
 suppose i want to do the following caulation for 100 times, how to put the
results of x , y and z into the same dataframe/dataset?

x<-runif(1)
y<-x+1
z<-x+y

thanks in advance!


-- 
Kind Regards,
Zhi Jie,Zhang ,PHD
Department of Epidemiology
School of Public Health
Fudan University
Tel:86-21-54237149

	[[alternative HTML version deleted]]

Dear Zhi Jie, Zhang,

This problem seems so straightforward that I wonder whether I
misunderstand what you want:

x <- runif(100)
y <- x + 1
z <- x + y
Data <- data.frame(x, y, z)

I hope this helps,
 John

On Tue, 20 Jun 2006 09:09:16 +0800
 "zhijie zhang" <epistat at gmail.com>
wrote:
> Dear friends,
>  suppose i want to do the following caulation for 100 times, how to
> put the
> results of x , y and z into the same dataframe/dataset?
> x<-runif(1)
> y<-x+1
> z<-x+y
> 
> thanks in advance!
> -- 
> Kind Regards,
> Zhi Jie,Zhang ,PHD
> Department of Epidemiology
> School of Public Health
> Fudan University
> Tel:86-21-54237149
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario, Canada
http://socserv.mcmaster.ca/jfox/

On Tue, Jun 20, 2006 at 09:09:16AM +0800, zhijie zhang
wrote:
>  suppose i want to do the following caulation for 100 times, how to put the
> results of x , y and z into the same dataframe/dataset?
> x<-runif(1)
> y<-x+1
> z<-x+y
Several possibilities:

1) Use rbind

Before loop:

d = NULL

And in the loop:

d = rbind(d, data.frame(x, y, z))


2) Build empty data frame of desired size beforehand and fill by row

E.g. for 10 rows:
d = data.frame( x=rep(0, 10), y=rep(0,10), z=rep(0,10))

And in the loop (index i):

d[i, ] = c(x, y, z)


3) Build vectors first, dataframe after the loop

x = NULL
y = NULL
z = NULL

in the loop:

x = append(x, runif(1))
...

After loop:

d = data.frame(x, y, z)

Solutions 1&3 are slower but you don't need to know the final number of
rows in advance. Solution 2 is cleaner, in my opinion, but requires that
you know the final size.

Of course, for the particular example calculation you don't need a loop
at all:

x = runif(100)
y = x+1
z = x+y
d = data.frame(x,y,z)

cu
	Philipp

-- 
Dr. Philipp Pagel                            Tel.  +49-8161-71 2131
Dept. of Genome Oriented Bioinformatics      Fax.  +49-8161-71 2186
Technical University of Munich
Science Center Weihenstephan
85350 Freising, Germany

 and

Institute for Bioinformatics / MIPS          Tel.  +49-89-3187 3675
GSF - National Research Center               Fax.  +49-89-3187 3585
      for Environment and Health
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85764 Neuherberg, Germany
http://mips.gsf.de/staff/pagel