Add option (and warning statement") about installing to user site pac…

…kages with `--user` flag for #10

 - this is one of those "necessary footguns"

R/install_rosetta.R

@@ -7,7 +7,9 @@
 #' @param conda Default: `"auto"`
 #' @param pip _logical_. Use `pip` for package installation? Default: `TRUE`. This is only relevant when Conda environments are used, as otherwise packages will be installed from the Conda repositories.
 #' @param system _logical_. Default: `FALSE`. If `TRUE`, try installing to system (user) site library with `system()` and set reticulate to use system Python.
+#' @param user _logical_. Default: `FALSE`. Pass `--user` flag. This should only be done if other installation methods fail and it is impossible to use a virtual environment.
 #' @param arcpy_path Argument passed to `find_python()`. Path to ArcGIS Pro Python installation e.g. ``. Set as `NULL` (default) to prevent use of ArcGIS Pro instance.
+#'
 #' @details From `reticulate::py_install()`: On Linux and OS X the "virtualenv" method will be used by default ("conda" will be used if virtualenv isn't available). On Windows, the "conda" method is always used.
 #'
 #' @export
@@ -18,19 +20,23 @@ install_rosetta <- function(envname = NULL,
                             method = "auto",
                             conda = "auto",
                             pip = TRUE,
+                            user = FALSE,
                             system = FALSE,
                             arcpy_path = getOption("rosettaPTF.arcpy_path")) {
 
   # use heuristics to find python executable
-  if (!is.null(arcpy_path) && dir.exists(arcpy_path)){
-    find_python(envname = envname, arcpy_path = arcpy_path)
+  if (!is.null(arcpy_path) && dir.exists(arcpy_path)) {
+    p <- find_python(envname = envname, arcpy_path = arcpy_path)
+    system <- TRUE
+  } else {
+    p <- Sys.which("python")
   }
 
-  if (isFALSE(system)){
+  if (isFALSE(system)) {
     # get rosetta-soil (and numpy if needed)
-    try(reticulate::py_install("rosetta-soil", envname = envname, method = method, conda = conda, pip = pip))
+    try(reticulate::py_install("rosetta-soil", envname = envname, method = method,
+                               conda = conda, pip = pip, pip_options = ifelse(user, "--user", "")))
   } else {
-    p <- Sys.which("python")
     reticulate::use_python(p, required = TRUE)
     system(paste(shQuote(p), "-m pip install --upgrade --user rosetta-soil"))
   }