[SPARK-9318] [SPARK-9320] [SPARKR] Aliases for merge and summary functions on DataFrames

This PR adds synonyms for ```merge``` and ```summary``` in SparkR DataFrame API.

cc shivaram

Author: Hossein <hossein@databricks.com>

Closes #7806 from falaki/SPARK-9320 and squashes the following commits:

72600f7 [Hossein] Updated docs
92a6e75 [Hossein] Fixed merge generic signature issue
4c2b051 [Hossein] Fixing naming with mllib summary
0f3a64c [Hossein] Added ... to generic for merge
30fbaf8 [Hossein] Merged master
ae1a4cf [Hossein] Merge branch 'master' into SPARK-9320
e8eb86f [Hossein] Add a generic for merge
fc01f2d [Hossein] Added unit test
8d92012 [Hossein] Added merge as an alias for join
5b8bedc [Hossein] Added unit test
632693d [Hossein] Added summary as an alias for describe for DataFrame

5 files changed, 48 insertions, 6 deletions

diff --git a/R/pkg/NAMESPACE b/R/pkg/NAMESPACE
index ff116cb1fb..b2d92bdf48 100644
--- a/R/pkg/NAMESPACE
+++ b/R/pkg/NAMESPACE
@@ -46,6 +46,7 @@ exportMethods("arrange",
               "isLocal",
               "join",
               "limit",
+              "merge",
               "names",
               "ncol",
               "nrow",
@@ -69,6 +70,7 @@ exportMethods("arrange",
               "show",
               "showDF",
               "summarize",
+              "summary",
               "take",
               "unionAll",
               "unique",
diff --git a/R/pkg/R/DataFrame.R b/R/pkg/R/DataFrame.R
index b4065d2944..8956032350 100644
--- a/R/pkg/R/DataFrame.R
+++ b/R/pkg/R/DataFrame.R
@@ -1279,6 +1279,15 @@ setMethod("join",
             dataFrame(sdf)
           })
 
+#' rdname merge
+#' aliases join
+setMethod("merge",
+          signature(x = "DataFrame", y = "DataFrame"),
+          function(x, y, joinExpr = NULL, joinType = NULL, ...) {
+            join(x, y, joinExpr, joinType)
+          })
+
+
 #' UnionAll
 #'
 #' Return a new DataFrame containing the union of rows in this DataFrame
@@ -1524,6 +1533,19 @@ setMethod("describe",
             dataFrame(sdf)
           })
 
+#' @title Summary
+#'
+#' @description Computes statistics for numeric columns of the DataFrame
+#'
+#' @rdname summary
+#' @aliases describe
+setMethod("summary",
+          signature(x = "DataFrame"),
+          function(x) {
+            describe(x)
+          })
+
+
 #' dropna
 #'
 #' Returns a new DataFrame omitting rows with null values.
diff --git a/R/pkg/R/generics.R b/R/pkg/R/generics.R
index 71d1e348c4..c43b947129 100644
--- a/R/pkg/R/generics.R
+++ b/R/pkg/R/generics.R
@@ -461,6 +461,10 @@ setGeneric("isLocal", function(x) { standardGeneric("isLocal") })
 #' @export
 setGeneric("limit", function(x, num) {standardGeneric("limit") })
 
+#' rdname merge
+#' @export
+setGeneric("merge")
+
 #' @rdname withColumn
 #' @export
 setGeneric("mutate", function(x, ...) {standardGeneric("mutate") })
@@ -531,6 +535,10 @@ setGeneric("showDF", function(x,...) { standardGeneric("showDF") })
 #' @export
 setGeneric("summarize", function(x,...) { standardGeneric("summarize") })
 
+##' rdname summary
+##' @export
+setGeneric("summary", function(x, ...) { standardGeneric("summary") })
+
 # @rdname tojson
 # @export
 setGeneric("toJSON", function(x) { standardGeneric("toJSON") })
diff --git a/R/pkg/R/mllib.R b/R/pkg/R/mllib.R
index efddcc1d8d..b524d1fd87 100644
--- a/R/pkg/R/mllib.R
+++ b/R/pkg/R/mllib.R
@@ -86,12 +86,12 @@ setMethod("predict", signature(object = "PipelineModel"),
 #' model <- glm(y ~ x, trainingData)
 #' summary(model)
 #'}
-setMethod("summary", signature(object = "PipelineModel"),
-          function(object) {
+setMethod("summary", signature(x = "PipelineModel"),
+          function(x, ...) {
             features <- callJStatic("org.apache.spark.ml.api.r.SparkRWrappers",
-                                   "getModelFeatures", object@model)
+                                   "getModelFeatures", x@model)
             weights <- callJStatic("org.apache.spark.ml.api.r.SparkRWrappers",
-                                   "getModelWeights", object@model)
+                                   "getModelWeights", x@model)
             coefficients <- as.matrix(unlist(weights))
             colnames(coefficients) <- c("Estimate")
             rownames(coefficients) <- unlist(features)
diff --git a/R/pkg/inst/tests/test_sparkSQL.R b/R/pkg/inst/tests/test_sparkSQL.R
index 9faee8d59c..7377fc8f1c 100644
--- a/R/pkg/inst/tests/test_sparkSQL.R
+++ b/R/pkg/inst/tests/test_sparkSQL.R
@@ -765,7 +765,7 @@ test_that("filter() on a DataFrame", {
   expect_equal(count(filtered6), 2)
 })
 
-test_that("join() on a DataFrame", {
+test_that("join() and merge() on a DataFrame", {
   df <- jsonFile(sqlContext, jsonPath)
 
   mockLines2 <- c("{\"name\":\"Michael\", \"test\": \"yes\"}",
@@ -794,6 +794,12 @@ test_that("join() on a DataFrame", {
   expect_equal(names(joined4), c("newAge", "name", "test"))
   expect_equal(count(joined4), 4)
   expect_equal(collect(orderBy(joined4, joined4$name))$newAge[3], 24)
+
+  merged <- select(merge(df, df2, df$name == df2$name, "outer"),
+                   alias(df$age + 5, "newAge"), df$name, df2$test)
+  expect_equal(names(merged), c("newAge", "name", "test"))
+  expect_equal(count(merged), 4)
+  expect_equal(collect(orderBy(merged, joined4$name))$newAge[3], 24)
 })
 
 test_that("toJSON() returns an RDD of the correct values", {
@@ -899,7 +905,7 @@ test_that("parquetFile works with multiple input paths", {
   expect_equal(count(parquetDF), count(df) * 2)
 })
 
-test_that("describe() on a DataFrame", {
+test_that("describe() and summarize() on a DataFrame", {
   df <- jsonFile(sqlContext, jsonPath)
   stats <- describe(df, "age")
   expect_equal(collect(stats)[1, "summary"], "count")
@@ -908,6 +914,10 @@ test_that("describe() on a DataFrame", {
   stats <- describe(df)
   expect_equal(collect(stats)[4, "name"], "Andy")
   expect_equal(collect(stats)[5, "age"], "30")
+
+  stats2 <- summary(df)
+  expect_equal(collect(stats2)[4, "name"], "Andy")
+  expect_equal(collect(stats2)[5, "age"], "30")
 })
 
 test_that("dropna() on a DataFrame", {