ARROW-7919: [R] install_arrow() should conda install if appropriate

Closes #6709 from nealrichardson/r-conda-install-arrow

Authored-by: Neal Richardson <neal.p.richardson@gmail.com>
Signed-off-by: Wes McKinney <wesm+git@apache.org>

r/R/install-arrow.R

@@ -36,7 +36,7 @@
 #' faster, but there is a risk of version mismatch.
 #' @param minimal logical: If building from source, should we build without
 #' optional dependencies (compression libraries, for example)? Default is
-#' `FALSE`. 
+#' `FALSE`.
 #' @param repos character vector of base URLs of the repositories to install
 #' from (passed to `install.packages()`)
 #' @param ... Additional arguments passed to `install.packages()`
@@ -51,14 +51,21 @@ install_arrow <- function(nightly = FALSE,
                           minimal = Sys.getenv("LIBARROW_MINIMAL", FALSE),
                           repos = getOption("repos"),
                           ...) {
-  if (tolower(Sys.info()[["sysname"]]) %in% c("windows", "darwin", "linux")) {
-    Sys.setenv(
-      LIBARROW_DOWNLOAD = "true",
-      LIBARROW_BINARY = binary,
-      LIBARRWOW_MINIMAL = minimal,
-      ARROW_USE_PKG_CONFIG = use_system
-    )
-    install.packages("arrow", repos = arrow_repos(repos, nightly), ...)
+  sysname <- tolower(Sys.info()[["sysname"]])
+  conda <- isTRUE(grepl("conda", R.Version()$platform))
+
+  if (sysname %in% c("windows", "darwin", "linux")) {
+    if (conda && !nightly && (sysname %in% c("darwin", "linux"))) {
+      system("conda install -y -c conda-forge --strict-channel-priority r-arrow")
+    } else {
+      Sys.setenv(
+        LIBARROW_DOWNLOAD = "true",
+        LIBARROW_BINARY = binary,
+        LIBARRWOW_MINIMAL = minimal,
+        ARROW_USE_PKG_CONFIG = use_system
+      )
+      install.packages("arrow", repos = arrow_repos(repos, nightly), ...)
+    }
     if ("arrow" %in% loadedNamespaces()) {
       # If you've just sourced this file, "arrow" won't be (re)loaded
       reload_arrow()

r/README.md

@@ -57,7 +57,7 @@ install_arrow()
 
 Conda users on Linux and macOS can install `arrow` from conda-forge with
 
-    conda install -c conda-forge r-arrow
+    conda install -c conda-forge --strict-channel-priority r-arrow
 
 ## Installing a development version
 

r/vignettes/install.Rmd

@@ -24,7 +24,7 @@ The intended audience for this document is `arrow` R package users on Linux, not
 If you're contributing to the Arrow project,
 you'll probably want to manage your C++ installation more directly.
 Note also that if you use `conda` to manage your R environment, this document does not apply.
-You can `conda install -c conda-forge r-arrow` and you'll get the latest official
+You can `conda install -c conda-forge --strict-channel-priority r-arrow` and you'll get the latest official
 release of the R package along with any C++ dependencies.
 
 # Installation basics