R/list_remote_files.R

In neurogenomics/MAGMA_Celltyping: Find Causal Cell-Types Underlying Complex Trait Genetics

#' List files  
#' 
#' List files on a remote server or website
#'
#' @param URL Web URL.
#' @param pattern Search pattern passed to \link[XML]{xpathSApply}.
#'
#' @source \href{https://stackoverflow.com/questions/15954463/read-list-of-file-names-from-web-into-r}{
#' stackoverflow}
#' 
#' @return List of remote files.
#' @keywords internal
#' @importFrom XML htmlParse xpathSApply free
list_remote_files <- function(URL,
                              pattern = "*.zip") {
 
    # doc <- rvest::read_html("https://vu.data.surfsara.nl/index.php/s/8qDPUbOTrZ9lW2b/")
    # rvest::html_elements(doc,"a")
    doc <- XML::htmlParse(readLines(URL), asText = TRUE)
    links <- XML::xpathSApply(doc, "//a/@href")
    XML::free(doc)
    wanted <- links[grepl(pattern = pattern, links)]
    GetMe <- paste(URL, unname(wanted), sep="/")
    names(GetMe) <- basename(GetMe)
    return(GetMe)
}