[SPARK-18788][SPARKR] Add API for getNumPartitions

## What changes were proposed in this pull request?

With doc to say this would convert DF into RDD

## How was this patch tested?

unit tests, manual tests

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #16668 from felixcheung/rgetnumpartitions.

2 files changed, 12 insertions, 12 deletions

diff --git a/R/pkg/inst/tests/testthat/test_rdd.R b/R/pkg/inst/tests/testthat/test_rdd.R
index 2c41a6b075..ceb31bd896 100644
--- a/R/pkg/inst/tests/testthat/test_rdd.R
+++ b/R/pkg/inst/tests/testthat/test_rdd.R
@@ -29,8 +29,8 @@ intPairs <- list(list(1L, -1), list(2L, 100), list(2L, 1), list(1L, 200))
 intRdd <- parallelize(sc, intPairs, 2L)
 
 test_that("get number of partitions in RDD", {
-  expect_equal(getNumPartitions(rdd), 2)
-  expect_equal(getNumPartitions(intRdd), 2)
+  expect_equal(getNumPartitionsRDD(rdd), 2)
+  expect_equal(getNumPartitionsRDD(intRdd), 2)
 })
 
 test_that("first on RDD", {
@@ -305,18 +305,18 @@ test_that("repartition/coalesce on RDDs", {
 
   # repartition
   r1 <- repartitionRDD(rdd, 2)
-  expect_equal(getNumPartitions(r1), 2L)
+  expect_equal(getNumPartitionsRDD(r1), 2L)
   count <- length(collectPartition(r1, 0L))
   expect_true(count >= 8 && count <= 12)
 
   r2 <- repartitionRDD(rdd, 6)
-  expect_equal(getNumPartitions(r2), 6L)
+  expect_equal(getNumPartitionsRDD(r2), 6L)
   count <- length(collectPartition(r2, 0L))
   expect_true(count >= 0 && count <= 4)
 
   # coalesce
   r3 <- coalesce(rdd, 1)
-  expect_equal(getNumPartitions(r3), 1L)
+  expect_equal(getNumPartitionsRDD(r3), 1L)
   count <- length(collectPartition(r3, 0L))
   expect_equal(count, 20)
 })
diff --git a/R/pkg/inst/tests/testthat/test_sparkSQL.R b/R/pkg/inst/tests/testthat/test_sparkSQL.R
index aaa8fb498c..417a03ff61 100644
--- a/R/pkg/inst/tests/testthat/test_sparkSQL.R
+++ b/R/pkg/inst/tests/testthat/test_sparkSQL.R
@@ -196,18 +196,18 @@ test_that("create DataFrame from RDD", {
   expect_equal(dtypes(df), list(c("name", "string"), c("age", "int"), c("height", "float")))
   expect_equal(as.list(collect(where(df, df$name == "John"))),
                list(name = "John", age = 19L, height = 176.5))
-  expect_equal(getNumPartitions(toRDD(df)), 1)
+  expect_equal(getNumPartitions(df), 1)
 
   df <- as.DataFrame(cars, numPartitions = 2)
-  expect_equal(getNumPartitions(toRDD(df)), 2)
+  expect_equal(getNumPartitions(df), 2)
   df <- createDataFrame(cars, numPartitions = 3)
-  expect_equal(getNumPartitions(toRDD(df)), 3)
+  expect_equal(getNumPartitions(df), 3)
   # validate limit by num of rows
   df <- createDataFrame(cars, numPartitions = 60)
-  expect_equal(getNumPartitions(toRDD(df)), 50)
+  expect_equal(getNumPartitions(df), 50)
   # validate when 1 < (length(coll) / numSlices) << length(coll)
   df <- createDataFrame(cars, numPartitions = 20)
-  expect_equal(getNumPartitions(toRDD(df)), 20)
+  expect_equal(getNumPartitions(df), 20)
 
   df <- as.DataFrame(data.frame(0))
   expect_is(df, "SparkDataFrame")
@@ -215,7 +215,7 @@ test_that("create DataFrame from RDD", {
   expect_is(df, "SparkDataFrame")
   df <- as.DataFrame(data.frame(0), numPartitions = 2)
   # no data to partition, goes to 1
-  expect_equal(getNumPartitions(toRDD(df)), 1)
+  expect_equal(getNumPartitions(df), 1)
 
   setHiveContext(sc)
   sql("CREATE TABLE people (name string, age double, height float)")
@@ -234,7 +234,7 @@ test_that("createDataFrame uses files for large objects", {
   conf <- callJMethod(sparkSession, "conf")
   callJMethod(conf, "set", "spark.r.maxAllocationLimit", "100")
   df <- suppressWarnings(createDataFrame(iris, numPartitions = 3))
-  expect_equal(getNumPartitions(toRDD(df)), 3)
+  expect_equal(getNumPartitions(df), 3)
 
   # Resetting the conf back to default value
   callJMethod(conf, "set", "spark.r.maxAllocationLimit", toString(.Machine$integer.max / 10))