R/find_python.R

In ncss-tech/rosettaPTF: R Frontend for Rosetta Pedotransfer Functions

#' Heuristics to Find Python
#'
#' If you are using the \{rosettaPTF\} package for the first time you will need to have Python installed to obtain the necessary modules. You can set up \{reticulate\} to install into a virtual or Conda environment. Usually \{reticulate\} should cover most or all of the setup.
#'
#' @param envname As in `reticulate::py_install()`:	The name, or full path, of the environment in which Python packages are to be installed. When NULL (the default), the active environment as set by the RETICULATE_PYTHON_ENV variable will be used; if that is unset, then the r-reticulate environment will be used.
#' @param pypath Optional: Path to `python` executable
#' @param arcpy_path Optional: Path to ArcGIS Pro Python installation. For example: `"C:/Program Files/ArcGIS/Pro/bin/Python"`. Set as `NULL` to prevent use of ArcGIS Pro instance.
#'
#'@details
#' If you have Python set up correctly you should be able to run `reticulate::py_config()` or `reticulate::py_discover_config()` and discover your shared library.
#'
#' A common problem with \{reticulate\} is not pointing at the correct (or any) `python` binary or `libpython` shared library. Use `reticulate::use_python("/path/to/python", required = TRUE)` to set the path or, alternately, be sure `python` can be found on your PATH. \{reticulate\} has a preference for Python environments that have `numpy` installed.
#'
#' ### Windows / Miniconda
#'
#' Use `reticulate::install_miniconda()` if you'd like to install a Miniconda Python environment. Conda is default on Windows.
#'
#' For devices with limited ability to install new software that have ArcGIS Pro installed (some USDA computers), this method can look for a Python installation in `"C:/Program Files/ArcGIS/Pro/bin/Python/envs/arcgispro-py3"` and Conda executable in `"C:/Program Files/ArcGIS/Pro/bin/Python/Scripts"`. The base file path to "Python" directory can be customized using the `arcpy_path` argument.
#'
#' ### Linux and OS X
#'
#' On Linux and OS X you can create a virtual environment using `reticulate::virtualenv_create()`. The default environment name will be `"r-reticulate"`.
#'
#' @return character path to `python` or `NULL` if no suitable environment can be found. The result is stored as the package option `rosettaPTF.python_path`.
#'
#' @export
#'
#' @examples
#'
#' find_python()
#'
#' @importFrom reticulate use_python use_condaenv conda_binary py_config py_discover_config
find_python <- function(envname = NULL,
                        pypath = NULL,
                        arcpy_path = getOption("rosettaPTF.arcpy_path")) {

  if (is.null(envname)) {
    envname <- Sys.getenv("RETICULATE_PYTHON_ENV", unset = "r-reticulate")
  }

  if (is.null(pypath)) {
    pypath_before <- getOption("rosettaPTF.python_path", default = NULL)
  } else{
    pypath_before <- pypath
  }

  if (is.null(pypath_before)) {
    pypath <- try(.find_python(envname = envname, pypath = pypath_before, arcpy_path = arcpy_path), silent = TRUE)

    if (!inherits(pypath, 'try-error')) {
      options(rosettaPTF.python_path = pypath)
    }

  }

  getOption("rosettaPTF.python_path")
}

.find_python <- function(envname = "r-reticulate",
                         pypath = getOption("rosettaPTF.python_path", default = NULL),
                         arcpy_path = getOption("rosettaPTF.arcpy_path", default = NULL)) {

  # check for ArcPro environment python EXE, and use it if present (USDA non-privileged machines)
  ARCPY_PATH <- file.path(arcpy_path, "envs/arcgispro-py3")
  PYEXE_PATH <- file.path(ARCPY_PATH, "python.exe")
  CONDA_PATH <- file.path(arcpy_path, "Scripts/conda.exe")

  res <- NULL
  if (length(pypath) == 0) {

    # find newest python installation with rosetta installed
    x <- try(reticulate::py_discover_config("rosetta"), silent = TRUE)
    if (!is.null(x$python_versions)) {
      xxx <- lapply(x$python_versions, function(x) {
        y <- gsub("Python ", "", system(paste(shQuote(x), "--version"), intern = TRUE, ignore.stdout = TRUE, ignore.stderr = TRUE))
        if (length(y) == 0) return("0")
        y
      })
      idx <- which.max(order(as.character(xxx)))
      res <- try(reticulate::use_python(x$python_versions[idx]), silent = TRUE)
    }

    # otherwise find newest python installation
    if (is.null(res) || inherits(res, 'try-error')) {
      x <- try(reticulate::py_discover_config(), silent = TRUE)
      if (!is.null(x$python_versions)) {
        xxx <- lapply(x$python_versions, function(x) {
          y <- gsub("Python ", "", system(paste(shQuote(x), "--version"), intern = TRUE, ignore.stdout = TRUE, ignore.stderr = TRUE, show.output.on.console = FALSE))
          if (length(y) == 0) return("0")
          y
        })
        idx <- which.max(order(as.character(xxx)))
        res <- try(reticulate::use_python(x$python_versions[idx]), silent = TRUE)
      }
    }
  }

  # if ArcGIS Pro is installed
  if (length(PYEXE_PATH) > 0 && file.exists(PYEXE_PATH)) {

    message("\n\nUsing ArcGIS Pro conda environment/python.exe\n\n")

    res <- try( {

      subres <- reticulate::use_python(PYEXE_PATH, required = TRUE)
      reticulate::use_condaenv(ARCPY_PATH)

      options(reticulate.conda_binary = CONDA_PATH)
      options(rosettaPTF.python_path = PYEXE_PATH)
      options(rosettaPTF.arcpy_path = arcpy_path)

      subres[grep("envs/arcgispro-py3", subres, fixed = TRUE)]
    }, silent = FALSE)

  # User can/should use regular reticulate methods for this

  # user specified python
  } else if (length(pypath) > 0 && file.exists(pypath)) {

    res <- try(reticulate::use_python(pypath, required = TRUE), silent = TRUE)

  # other cases of Conda or virtualenv
  } else {
    # python path from py_config() result
    res <- try(reticulate::py_discover_config(use_environment = envname), silent = TRUE)
    if (!inherits(res, 'try-error')) {
      res <- res[["python"]]
      res <- try(reticulate::use_python(res, required = TRUE), silent = TRUE)
    }

  }

  if (inherits(res, 'try-error')) {
    stop(res, call. = FALSE)
  }

  try(reticulate::py_config(), silent = TRUE)
  res
}