[R] Using loop numbers in write.csv

[Greg Snow]

For filenames you can do something like:

 file = paste("resultsMatrix_', i, sep='')

For naming objects in the workspace, there is a way, but you really
don't want to do that.  It is better to store them in a list, for
example:

resultList <- list()
for( i in 1:10){
     	resultList[[i]] <-  matrix(runif(25, 0, 1),5, 5)
   }

If you want the elements of the list named you can do:

names( resultList ) <- paste('resultMatrix_',1:10, sep='')

Now you have 10 matricies all grouped together in a list, you can access
a single matrix like resultList[[1]] or resultList$resultMatrix_1, or
you can do something to all of them using lapply or sapply.  You are
much less likely to overwrite data by accident, you can save, copy,
load, delete, etc the whole set in 1 step rather than using a loop.

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
(801) 408-8111
 
 

> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Economics Guy
> Sent: Thursday, March 13, 2008 11:07 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Using loop numbers in write.csv
> 
> This is a question I have wanted to ask for a while but 
> hesitated because I was sut sure I would find the answer on 
> my own, but as of yet...no dice.
> 
> 1) Is there a way to use the loop number in naming things in R.
> Specifically I have  a simulation that has two loops. I would 
> like to be able to write out the results to a csv file after 
> each iteration.
> 
> something like:
> 
> 
>         for (i in 1:10){
>         	
>         	exampleMatrix <-  matrix(runif(25, 0, 1),5, 5)
>         	
>         	write.csv(exampleMatrix, file = "resultsMatrix_i.csv")
>         	
>         	}
> 
> Where I would get 10 csv files named resultsMatrix_1, 
> resultsMatrix_2 ... resultsMatrix_10.
> 
> 
> 2) On a similar note is there a way to use the loop number 
> when naming things.
> 
> something like:
> 
> 
>         for (i in 1:10){
>         	
>         	exampleMatrix_i <-  matrix(runif(25, 0, 1),5, 5)
>         	
>         	}
> 
> Where I would then have 10 matrices in memory with the names 
> exampleMatrix_1, exampleMatrix_2 ... exampleMatrix_10.
> 
> Thanks,
> 
> EG
> 
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