R使用Rcurl从FTP下载多个文件

Question

I'm a new R. user. I am trying to download 7.000 files(.nc format) from ftp server ( which I got from user and password). On the website, each file is a link to download. I would like to download all the files (.nc).

I thank anyone who can help me how to run those jobs in R. Just an example what I have tried to do using Rcurl and a loop and informs me: cannot download all files.

library(RCurl)

url<- "ftp://ftp.my.link.fr/1234/"
userpwd <- userpwd="user:password"
destination <- "/Users/ME/Documents"
filenames <- getURL(url, userpwd="user:password", 
ftp.use.epsv = FALSE, dirlistonly = TRUE)

for(i in seq_along(url)){
  download.file(url[i], destination[i], mode="wb")
}

how can I do that?

Answer 1

The first thing you'd see is that the files in your directory, ie the object filenames , would be listed as one long string. To obtain an object of all file names as a character vector, you may try:

    files <- unlist(strsplit(filenames, '\n'))

From here on, it's simply a matter of looping through all the files in the directory. I recommend you use the curl package, not Rcurl, to download the files, as it's easier to supply auth info for every download request.

    library(curl)
    h <- new_handle()
    handle_setopt(h, userpwd = "user:pwd")

and then

    lapply(files, function(filename){
    curl_download(paste(url, filename, sep = ""), destfile = filename, handle = h)
    })