R help - Dec 2005 - Construct a data.frame in a FOR-loop

Say I have a FOR-loop for computing powers (just a trivial example)

for(i in 1:5)
{
	x<-i^2
	y<-i^3
}

How can I create a data.frame and a 3D plot of (i,x(i),y(i)), i.e. for 
each iteration

Thanks,
Serguei Kaniovski
-- 
___________________________________________________________________

??sterreichisches Institut f??r Wirtschaftsforschung (WIFO)

Name: Serguei Kaniovski                 Postadresse: Postfach  91
Tel.: +43-1-7982601-231                 A-1103  Wien
Fax : +43-1-7989386                     Standort: Arsenal Objekt 20 

Mail: Serguei.Kaniovski at wifo.ac.at      A-1030  Wien

http://www.wifo.ac.at/

>Say I have a FOR-loop for computing powers (just a trivial example)
>
>for(i in 1:5)
>{
>	x<-i^2
>	y<-i^3
>}
>
>How can I create a data.frame 
> x<-numeric(5)
> y<-numeric(5)
> for(i in 1:5)
+ {
+ x[i]<-i^2
+ y[i]<-i^3
+ }
> da<-data.frame(index=1:5,x=x,y=y)
> da
  index  x   y
1     1  1   1
2     2  4   8
3     3  9  27
4     4 16  64
5     5 25 125

these can get the data frame.
>and a 3D plot of (i,x(i),y(i)), i.e. for 
>each iteration
>
>Thanks,
>Serguei Kaniovski
>-- 
>___________________________________________________________________
>
>佒sterreichisches Institut f侟r Wirtschaftsforschung (WIFO)
>
>Name: Serguei Kaniovski                 Postadresse: Postfach  91
>Tel.: +43-1-7982601-231                 A-1103  Wien
>Fax : +43-1-7989386                     Standort: Arsenal Objekt 20 
>
>Mail: Serguei.Kaniovski at wifo.ac.at      A-1030  Wien
>
>http://www.wifo.ac.at/
>
>______________________________________________
>R-help at stat.math.ethz.ch mailing list
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>PLEASE do read the posting guide!
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2005-12-04

------
Deparment of Sociology
Fudan University

My new mail addres is ronggui.huang at gmail.com
Blog:http://sociology.yculblog.com

Serguei Kaniovski wrote:
> Say I have a FOR-loop for computing powers (just a trivial example)
> 
> for(i in 1:5)
> {
> x<-i^2
> y<-i^3
> }
> 
> How can I create a data.frame and a 3D plot of (i,x(i),y(i)), i.e. for
> each iteration
> 
> Thanks,
> Serguei Kaniovski
If thats all you really need:
data<- t(sapply(1:5, function(i){ return(c(i,i^2,i^3))}))
scatterplot3d(data)

In general you don't plot something in R for each iteration.
You rather pass the whole result to the plot function.
But there are plotting function which accept formulas.

Regards,
Ido Tamir

Serguei Kaniovski wrote:
> Say I have a FOR-loop for computing powers (just a trivial example)
> for(i in 1:5)
> {
> 	x<-i^2
> 	y<-i^3
> }
> 
> How can I create a data.frame and a 3D plot of (i,x(i),y(i)), i.e. for 
> each iteration
First of all you can easily avoid for-loops in such examples.
You can better work with matrices, so just do
R> i <- 1:5
R> x <- i^2
R> y <- i^3

Second, maybe very interesting, if you want to look somethimg up and do 
not know the R-command. You can always try with RSiteSearch("...").

I'm not sure what you mean with ``construct a data.frame in a for 
loop''. As far as I know you can better first do the loop and construct 
at the end the data.frame. Anyway, to create a data.frame, you can e.g. do
R> resdf <- as.data.frame(cbind(i,x,y))

To create 3D-plot there are seeral possibilities.
Try   ?persp (for surfaces)
or you can download the scatterplot3d package available on CRAN (for 
points and lines).

Hopefully this helps,
Good luck,
Kristel

Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm

I think I know what you would like to have.

Sometyhing you can do
R> res<-vector("list",5)
R> for (i in 1:5)
R> {...
R>   res[[i]]=my_code(i)
R> }

As an easy example:
R> res<-vector("list",5)
R> for (i in 1:5){res[[i]]=1:i}
R> ex
[[1]]
[1] 1

[[2]]
[1] 1 2

[[3]]
[1] 1 2 3

[[4]]
[1] 1 2 3 4

[[5]]
[1] 1 2 3 4 5


Best regards,
Kristel

-- 
__________________________________________
Kristel Joossens        Ph.D. Student
Research Center ORSTAT  K.U. Leuven
Naamsestraat 69         Tel: +32 16 326929
3000 Leuven, Belgium    Fax: +32 16 326732
E-mail:  Kristel.Joossens at econ.kuleuven.be
http://www.econ.kuleuven.be/public/ndbae49




Serguei Kaniovski wrote:
> Hi, thanks for your reply. What I have is a large chunk of code 
> "my_code" that is controlled by a single FOR-loop. The code
computes a
> single value my_code(i) depending on the loop counter i. What I would 
> like to do is to organize the input and the output into a table so that 
> it can be e.g. plotted, for example in this format
> 
> input_i        i=1        i=2        i=3    ....
>         my_code(1)    my_code(2)    my_code(3)
> ...
> 
> where my_code(1) is the output of a single iteration, itself a column 
> vector of variable size N(i)
> 
> Serguei
> 
> Kristel Joossens schrieb:
> 
>> Serguei Kaniovski wrote:
>>
>>> Say I have a FOR-loop for computing powers (just a trivial example)
>>> for(i in 1:5)
>>> {
>>>     x<-i^2
>>>     y<-i^3
>>> }
>>>
>>> How can I create a data.frame and a 3D plot of (i,x(i),y(i)), i.e. 
>>> for each iteration
>>
>>
>>
>> First of all you can easily avoid for-loops in such examples.
>> You can better work with matrices, so just do
>> R> i <- 1:5
>> R> x <- i^2
>> R> y <- i^3
>>
>> Second, maybe very interesting, if you want to look somethimg up and 
>> do not know the R-command. You can always try with
RSiteSearch("...").
>>
>> I'm not sure what you mean with ``construct a data.frame in a for 
>> loop''. As far as I know you can better first do the loop and 
>> construct at the end the data.frame. Anyway, to create a data.frame, 
>> you can e.g. do
>> R> resdf <- as.data.frame(cbind(i,x,y))
>>
>> To create 3D-plot there are seeral possibilities.
>> Try   ?persp (for surfaces)
>> or you can download the scatterplot3d package available on CRAN (for 
>> points and lines).
>>
>> Hopefully this helps,
>> Good luck,
>> Kristel


Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm