[R] Indexing within scan

[Peter Dalgaard]

"Justin Rhodes" <rhodesju at ohsu.edu> writes:

> Dear R-help subscribers,
> 
> Can some one please help me figure out how to write code that will allow me to use a for loop to scan a number of files one by one, and then save a summary of each file as the for loop progresses.  For example I have 24 files named a1 through a24, and I want to do something like:
> 
> 
> results<-numeric(24)
> for (i in 1:24)
> {
>  
> p<-scan("ai.txt")  # where the i is an index for each of the 24 files
> 
> results[i]<-mean(p)
> }
> 
> Thanks for any help,
> 

paste("a", i, ".txt", sep="") 

should get you in the right direction. However, I don't think you
*really* want a for loop. Use vectorization and sapply instead:

names <- paste("a", 1:24, ".txt", sep="")
results <- sapply(names, function(n) mean(scan(n)) )

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