[R-sig-Geo] getting subfolders in a directory on FTP (MODIS)

[Tomislav Hengl]

Hey Barry,

Your code works fine (at least with the NASA ftps). Thanks!

I knew it - everything is possible in R  :) 

T. Hengl
http://spatial-analyst.net 


> -----Original Message-----
> From: b.rowlingson at googlemail.com [mailto:b.rowlingson at googlemail.com] On Behalf Of Barry
> Rowlingson
> Sent: Tuesday, July 14, 2009 4:53 PM
> To: Tomislav Hengl
> Cc: alexandre villers; r-sig-geo at stat.math.ethz.ch
> Subject: Re: [R-sig-Geo] getting subfolders in a directory on FTP (MODIS)
> 
> On Tue, Jul 14, 2009 at 2:12 PM, Tomislav
> Hengl<hengl at spatial-analyst.net> wrote:
> 
> > To tell you honestly, I could not figure out how to fetch names of sub-folders from an ftp
> (maybe it
> > is simply not possible?),
> 
>  Apparently the FTP spec doesn't specify how to return a list of
> directories, which, I read, "is a source of headaches to FTP client
> developers".
> 
>  If you do:
> 
>  resp = getURL("ftp://n4ftl01u.ecs.nasa.gov/SAN/MOST/MOD10CM.005/")
>  items = strsplit(resp,"\n")[[1]]
> 
> you get the folders (and files) but the folder names are in the form
> of a unix directory listing. So you then want the last word of any
> lines that start with 'd'. Lets get the lines first:
> 
>  folderLines = items[substr(items,1,1)=='d']
> 
> that gets you all the lines. There's probably a neater way of getting
> the last word than this:
> 
>  lastBit <- function(x){x[length(x)]}
> 
>  dirs = unlist(lapply(strsplit(folderLines," "),lastBit))
> 
> Note this only works on the FTP server specified, other FTP servers
> are at liberty to send back any dir format they want (I think I was
> surprised the first time I connected to a DOS-based FTP server and saw
> a DOS DIR listing!).
> 
> Barry