[R] Import the files.

David Scott d.scott at auckland.ac.nz
Thu Mar 5 21:57:10 CET 2009

On Thu, 5 Mar 2009, ling ling wrote:

> Dear all,
> I am a newcomer to R programming, I met the problem:
> I have a lot of .txt files in my directory.
> Firstly, I check whether the file satisfies the conditions:
> 1.empty
> 2.the "Rep" column of the file has no "useractivity_idle" or
> "useractivity_act"
> 3.even The "rep" has both of them, numbers of "useractivity_idle"==numbers of "useractivity_act"==1
> If the file has one of those conditions, skip this file, jump to and read the next .txt file:
> I made the programming as:
> name<-list.files(path = ".", pattern = NULL, all.files = FALSE,
>           full.names = FALSE, recursive = FALSE,
>           ignore.case = FALSE)
> for(k in 1:length(name)){
> log1<-read.table(name[k],header=TRUE,stringsAsFactors=FALSE)
> x<-which(log1$Rep=="useractivity_act")
> y<-which(log1$Rep=="useractivity_idle")
> while(all(log1$Rep!="useractivity_act")||all(log1$Rep!="useractivity_idle")||(length(x)==1 && length(y)==1)||(file.info(name[k])$size== 0)){
> k=k+1
> log1<-read.table(name[k],header=TRUE,stringsAsFactors=FALSE)
> }
> ........
> }
> But I always get the following information:
> Error in file(file, "r") : cannot open the connection
> In addition: Warning message:
> In file(file, "r") : cannot open file 'NA': No such file or directory
> I have been exploring this for long time, any help would be appreciated. Thanks a lot!
> Tammy

This is a bit of a guess but the message is saying it can't find the files 
it is expecting. That could be because your working directory is not what 
you think it is. Alternatively you have some name in your file list that 
is not in the directory you are looking at.

To debug, start by issuing the name <- statement. Check what it is in 
names? Is it what you think it should be?

Then do k <- 1 and start running through the commands *inside* your for 
loop. Check at each point that you have what you expect to have in log1, 
x, y etc.

Also check the for loop with k <- length(name). That looks like a possible 
problem with k=k+1 later in the loop.

By the way, your code is horrible. You should indent and space around more 
things ( <- for example). And either use = for assignment or <-, don't use 
both in the same bit of code.

David Scott

David Scott	Department of Statistics
 		The University of Auckland, PB 92019
 		Auckland 1142,    NEW ZEALAND
Phone: +64 9 373 7599 ext 85055		Fax: +64 9 373 7018
Email:	d.scott at auckland.ac.nz

Graduate Officer, Department of Statistics
Director of Consulting, Department of Statistics

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