Merge pull request apache#91 from sun-rui/add_max_min

Add maximum() and minimum() API to RDD.

pkg/NAMESPACE

@@ -21,6 +21,8 @@ exportMethods(
               "mapPartitions",
               "mapPartitionsWithIndex",
               "mapValues",
+              "maximum",
+              "minimum",
               "partitionBy",
               "reduce",
               "reduceByKey",

pkg/R/RDD.R

@@ -554,6 +554,48 @@ setMethod("reduce",
             Reduce(func, partitionList)
           })
 
+#' Get the maximum element of an RDD.
+#'
+#' @param rdd The RDD to get the maximum element from
+#' @export
+#' @rdname maximum
+#' @examples
+#'\dontrun{
+#' sc <- sparkR.init()
+#' rdd <- parallelize(sc, 1:10)
+#' maximum(rdd) # 10
+#'}
+setGeneric("maximum", function(rdd) { standardGeneric("maximum") })
+
+#' @rdname maximum
+#' @aliases maximum,RDD
+setMethod("maximum",
+          signature(rdd = "RDD"),
+          function(rdd) {
+            reduce(rdd, max)
+          })
+
+#' Get the minimum element of an RDD.
+#'
+#' @param rdd The RDD to get the minimum element from
+#' @export
+#' @rdname minimum
+#' @examples
+#'\dontrun{
+#' sc <- sparkR.init()
+#' rdd <- parallelize(sc, 1:10)
+#' minimum(rdd) # 1
+#'}
+setGeneric("minimum", function(rdd) { standardGeneric("minimum") })
+
+#' @rdname minimum
+#' @aliases minimum,RDD
+setMethod("minimum",
+          signature(rdd = "RDD"),
+          function(rdd) {
+            reduce(rdd, min)
+          })
+
 #' Take elements from an RDD.
 #'
 #' This function takes the first NUM elements in the RDD and

pkg/inst/tests/test_rdd.R

@@ -178,3 +178,13 @@ test_that("distinct() on RDDs", {
   actual <- sort(unlist(collect(uniques)))
   expect_equal(actual, nums)
 })
+
+test_that("maximum() on RDDs", {
+  max <- maximum(rdd)
+  expect_equal(max, 10)
+})
+
+test_that("minimum() on RDDs", {
+  min <- minimum(rdd)
+  expect_equal(min, 1)
+})

pkg/man/maximum.Rd

@@ -0,0 +1,26 @@
+% Generated by roxygen2 (4.0.2): do not edit by hand
+\docType{methods}
+\name{maximum}
+\alias{maximum}
+\alias{maximum,RDD}
+\alias{maximum,RDD-method}
+\title{Get the maximum element of an RDD.}
+\usage{
+maximum(rdd)
+
+\S4method{maximum}{RDD}(rdd)
+}
+\arguments{
+\item{rdd}{The RDD to get the maximum element from}
+}
+\description{
+Get the maximum element of an RDD.
+}
+\examples{
+\dontrun{
+sc <- sparkR.init()
+rdd <- parallelize(sc, 1:10)
+maximum(rdd) # 10
+}
+}
+

pkg/man/minimum.Rd

@@ -0,0 +1,26 @@
+% Generated by roxygen2 (4.0.2): do not edit by hand
+\docType{methods}
+\name{minimum}
+\alias{minimum}
+\alias{minimum,RDD}
+\alias{minimum,RDD-method}
+\title{Get the minimum element of an RDD.}
+\usage{
+minimum(rdd)
+
+\S4method{minimum}{RDD}(rdd)
+}
+\arguments{
+\item{rdd}{The RDD to get the minimum element from}
+}
+\description{
+Get the minimum element of an RDD.
+}
+\examples{
+\dontrun{
+sc <- sparkR.init()
+rdd <- parallelize(sc, 1:10)
+minimum(rdd) # 1
+}
+}
+