[R] Reading and coalescing many datafiles.

[Peter Dalgaard]

asr at ufl.edu writes:

> Greetings.
> 
> 
> I've got some analysis problems I'm trying to solve, the raw data for which
> are accumulated in a bunch of time-and-date-based files.
> 
> /some/path/2005-01-02-00-00-02
> 
> etc.
> 
> 
> The best 'read all these files' method I've seen in the r-help archives comes
> down to 
> 
> for (df in my_list_of_filenames )
>     {
>           dat <- rbind(dat,my_read_function(df))
>     } 
> 
> which, unpleasantly, is O(N^2) w.r.t. the number of files.
> 
> I'm fiddling with other idioms to accomplish the same goal.  Best I've come up
> with so far, after extensive reference to the mailing list archives, is
> 
> 
> my_read_function.many<-function(filenames)
>   {
>     filenames <- filenames[file.exists(filenames)];
>     rv <- do.call("rbind", lapply(filenames,my_read_function))
>     row.names(rv) = c(1:length(row.names(rv)))
>     rv
>   }
> 
> 
> I'd love to have some stupid omission pointed out.


Why? It's pretty much what I would suggest, except for the superfluous
c().

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907