[SPARK-8364] [SPARKR] Add crosstab to SparkR DataFrames

Add `crosstab` to SparkR DataFrames, which takes two column names and returns a local R data.frame. This is similar to `table` in R. However, `table` in SparkR is used for loading SQL tables as DataFrames. The return type is data.frame instead table for `crosstab` to be compatible with Scala/Python.

I couldn't run R tests successfully on my local. Many unit tests failed. So let's try Jenkins.

Author: Xiangrui Meng <meng@databricks.com>

Closes #7318 from mengxr/SPARK-8364 and squashes the following commits:

d75e894 [Xiangrui Meng] fix tests
53f6ddd [Xiangrui Meng] fix tests
f1348d6 [Xiangrui Meng] update test
47cb088 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-8364
5621262 [Xiangrui Meng] first version without test

1 files changed, 13 insertions, 0 deletions

diff --git a/R/pkg/inst/tests/test_sparkSQL.R b/R/pkg/inst/tests/test_sparkSQL.R
index a3039d36c9..62fe48a5d6 100644
--- a/R/pkg/inst/tests/test_sparkSQL.R
+++ b/R/pkg/inst/tests/test_sparkSQL.R
@@ -987,6 +987,19 @@ test_that("fillna() on a DataFrame", {
   expect_identical(expected, actual)
 })
 
+test_that("crosstab() on a DataFrame", {
+  rdd <- lapply(parallelize(sc, 0:3), function(x) {
+    list(paste0("a", x %% 3), paste0("b", x %% 2))
+  })
+  df <- toDF(rdd, list("a", "b"))
+  ct <- crosstab(df, "a", "b")
+  ordered <- ct[order(ct$a_b),]
+  row.names(ordered) <- NULL
+  expected <- data.frame("a_b" = c("a0", "a1", "a2"), "b0" = c(1, 0, 1), "b1" = c(1, 1, 0),
+                         stringsAsFactors = FALSE, row.names = NULL)
+  expect_identical(expected, ordered)
+})
+
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