Download data from web using R gives libcurl error - r

Question

I have the following R script for downloading data but it gives me an error. How can I fix this error?
rm(list=ls(all=TRUE))
library('purrr')
years <- c(1980:1981)
days <- c(001:002)
walk(years, function(x) {
map(x, ~sprintf("https://hydro1.gesdisc.eosdis.nasa.gov/data/NLDAS/NLDAS_MOS0125_H.002/%s/%s/.grb", years, days)) %>%
flatten_chr() -> urls
download.file(urls, basename(urls), method="libcurl")
})
Error:
Error in download.file(urls, basename(urls), method = "libcurl") :
download.file(method = "libcurl") is not supported on this platform
I have the following R script for downloading data but it gives me an error. How can I fix this error?
Session info:

Answer 1

That means that libcurl may not be installed or available for your operative system. Please note that the method argument has other options and that method varies across operative systems (more or less the same as platform in the error message). I would try with other methods (e.g., wget, curl...).
From the help of download.files...
The supported ‘method’s do change: method ‘libcurl’ was introduced
in R 3.2.0 and is still optional on Windows - use
‘capabilities("libcurl")’ in a program to see if it is available.

Answer 2

I had started to do a light edit to #gballench's answer (since I don't rly need the pts) but it's more complex than you have it since you're not going to get to the files you need with that idiom (which I'm 99% sure is from an answer of mine :-) for a whole host of reasons.
First days needs to be padded to length 3 with 0s but the way you did it won't do that. Second, You likely want to download all the .grb files from each year/00x combo, so you need a way to get those. Finally, that site requires authentication, so you need to register and use basic authentication for it.
Something like this:
library(purrr)
library(httr)
library(rvest)
years <- c(1980:1981)
days <- sprintf("%03d", 1:2)
sprintf("http://hydro1.gesdisc.eosdis.nasa.gov/data/NLDAS/NLDAS_MOS0125_H.002/%s/%%s/", years) %>%
map(~sprintf(.x, days)) %>%
flatten_chr() %>%
map(~{
base_url <- .x
sprintf("%s/%s", base_url, read_html(.x) %>%
html_nodes(xpath=".//a[contains(#href, '.grb')]") %>%
html_attr("href"))
}) %>%
flatten_chr() %>%
discard(~grepl("xml$", .)) %>%
walk(~{
output_path <- file.path("FULL DIRECTORY PATH", basename(.x))
if (!file.exists(output_path)) {
message(.x)
GET(
url = .x,
config = httr::config(ssl_verifypeer = FALSE),
write_disk(output_path, overwrite=TRUE),
authenticate(user = "me#example.com", password = "xldjkdjfid8y83"),
progress()
)
}
})
You'll need to install the httr package which will install the curl package and ultimately make libcurl available for simpler batch downloads in the future.
I remembered that I had an account so I linked it with this app & tested this (killed it at 30 downloads) and it works. I added progress() to the GET() call so you can see it downloading individual files. It skips over already downloaded files (so you can kill it and restart it at any time). If you need to re-download any, just remove the file you want to re-download.
If you also need the .xml files, then remove the discard() call.