[R] Repeating a series of commands

Jessica Streicher j.streicher at micromata.de
Fri Oct 12 12:02:36 CEST 2012

This is pretty confusing writeup, but if you have iterations, then yes, you need a loop or a recursion.

A loop is probably easier, take a look at 




for this.

there are several derivates of apply

for example, say your outputs are what the code below gives you for each file, then first make a vector with the files

then you can easily get the "results" (a$z,b$z) as another vector by using

outputs <- sapply(filevec,function(x){
	something<- ifelse(

and if you want to do this several times:

m<- matrix(ncol=length(filevec),nrow=10)
myResult<- as.data.frame(m)

for(i in 1:10){
	outputs <- sapply(filevec,function(x){
	something<- ifelse(

If you don't know the number of iterations or outputs beforehand, i'd have a look at "while" and use lists.

Hope this helps.

On 11.10.2012, at 20:09, KoopaTrooper wrote:

> I'm trying to figure out how to repeat a series of commands in R and have the
> outputs added to a dataframe after each iteration.
> My code starts this way...
> a<-read.csv("File1.csv")
> b<-read.csv("File2.csv")
> a$Z<-ifelse(a$Z=="L",sample(1:4,length(a$Z),replace=TRUE),ifelse(a$Z=="M",sample(5:8,length(a$Z),replace=TRUE),ifelse(a$Z=="U",sample(9:10,length(a$Z),replace=TRUE),"")))
> a$Z<-as.numeric(a$Z)
> b$Z<-ifelse(b$Z=="L",sample(1:4,length(b$Z),replace=TRUE),ifelse(b$Z=="M",sample(5:8,length(b$Z),replace=TRUE),ifelse(b$Z=="U",sample(9:10,length(b$Z),replace=TRUE),"")))
> b$Z<-as.numeric(b$Z)
> This is basically just starting off with a new and partially random data set
> every time that then goes through a bunch of other commands (not shown) and
> ends with the following outputs saved.
> Output1, Output2, Output3, Output4
> where each of these is just a single number. My questions is:
> 1. How do I repeat the entire series of commands x number of times and save
> each of the outputs into a structure like this:
>                      Output1      Output2     Output3     Output4
> Iteration 1
> Iteration 2
> Iteration 3
> etc.
> Not even sure where to start. Are loops the answer? Thanks,
> --
> View this message in context: http://r.789695.n4.nabble.com/Repeating-a-series-of-commands-tp4645881.html
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