R/ghdecompose.R

In mmstat4: Access to Teaching Materials from a ZIP File or GitHub

#' ghdecompose
#'
#' Decomposes a path of a set of files (or dirs) in several parts:
#'
#' * `outpath` the path part which is common to all files (basically the place where the ZIP file was extracted)
#' * `inpath` the path part which is not necessary for a unique address in teh ZIP file
#' * `minpath` the minimal path part such that all files addressable in unique manner,
#' * `filename` the basename of the file, and
#' * `source` the input to `shortpath`.
#'
#' @param files character vector: path of files
#' @param dirs logical: directory or files names (default: `FALSE`)
#'
#' @return a data frame with five variables
#' @export
#'
#' @examples
#' ghget("local")
#' pdf <- ghdecompose(ghlist(full.names=TRUE))
#' pdf
ghdecompose <- function (files, dirs=FALSE) {
  stopifnot(length(files)>0)
  sfiles <- strsplit(files, "[\\/]")
  path   <- character(0)
  i      <- 1
  if (length(files)>1) {
    npath <- min(lengths(sfiles))
    for (i in 1:npath) {
      pathi <- unique(sapply(sfiles, '[', i))
      if (length(pathi)>1) break
      path[i] <- pathi
    }
  }
  sfiles     <- lapply(sfiles, function(p) { rev(p[i:length(p)]) })
  upos       <- rep(-1, length(files))
  nonunique  <- (upos<0)
  i          <- 1
  while(any(nonunique)) {
    pfiles <- sapply(sfiles, function(p) { paste0(p[1:min(i,length(p))], collapse="/") })
    dups   <- duplicated(pfiles) | duplicated(pfiles, fromLast=TRUE)
    upos[nonunique & !dups] <- i
    nonunique  <- (upos<0)
    i <- i+1
  }
  inpath   <- sapply(1:length(files), function(i) { paste0(rev(sfiles[[i]][-(1:upos[i])]), collapse="/")} )
  minpath  <- sapply(1:length(files), function(i) { paste0(rev(sfiles[[i]][1:upos[i]]), collapse="/")} )
  filename <- rep('', length(files))
  if (!dirs) {
    filename <- basename(minpath)
    minpath  <- dirname(minpath)
  }
  df <- data.frame(outpath=rep(paste0(path, collapse="/"), length(files)),
#                   uniquepath=sapply(sfiles, i=i, function(v, i) { if (i<length(v)) paste0(v[(length(v)-1):i], collapse="/") else '' }),
                   inpath=inpath,
                   minpath=gsub('.', '', minpath, fixed=TRUE),
                   filename=filename,
                   source=files)
  structure(df, class=c("ghdecompose", class(df)))
}