## What changes were proposed in this pull request?

Replace

    note repeat_string 2.3.0

with

    note repeat_string since 2.3.0

## How was this patch tested?

`create-docs.sh`

Author: zero323 <zero323@users.noreply.github.com>

Closes #17779 from zero323/REPEAT-NOTE.

## What changes were proposed in this pull request?
This pr added a new display mode for `Dataset.show` to print output rows vertically (one line per column value). In the current master, when printing Dataset with many columns, the readability is low like;

```
scala> val df = spark.range(100).selectExpr((0 until 100).map(i => s"rand() AS c$i"): _*)
scala> df.show(3, 0)
+------------------+------------------+------------------+-------------------+------------------+------------------+-------------------+------------------+------------------+------------------+------------------+-------------------+------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+--------------------+-------------------+------------------+-------------------+--------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+--------------------+--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+--------------------+-------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+-------------------+------------------+-------------------+------------------+------------------+-----------------+-------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+------------------+-------------------+-------------------+------------------+------------------+------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+
|c0                |c1                |c2                |c3                 |c4                |c5                |c6                 |c7                |c8                |c9                |c10               |c11                |c12               |c13               |c14               |c15                |c16                |c17                |c18               |c19               |c20                |c21               |c22                |c23               |c24                |c25                |c26                |c27                 |c28                |c29               |c30                |c31                 |c32               |c33               |c34                |c35                |c36                |c37               |c38               |c39                |c40               |c41               |c42                |c43                |c44                |c45               |c46                 |c47                 |c48                |c49                |c50                |c51                |c52                |c53                |c54                 |c55                |c56                |c57                |c58                |c59               |c60               |c61                |c62                |c63               |c64                |c65               |c66               |c67              |c68                |c69                |c70               |c71                |c72               |c73                |c74                |c75                |c76               |c77                |c78               |c79                |c80                |c81                |c82                |c83                |c84                |c85                |c86                |c87               |c88                |c89                |c90               |c91               |c92               |c93                |c94               |c95                |c96               |c97                |c98                |c99                |
+------------------+------------------+------------------+-------------------+------------------+------------------+-------------------+------------------+------------------+------------------+------------------+-------------------+------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+--------------------+-------------------+------------------+-------------------+--------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+--------------------+--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+--------------------+-------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+-------------------+------------------+-------------------+------------------+------------------+-----------------+-------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+------------------+-------------------+-------------------+------------------+------------------+------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+
|0.6306087152476858|0.9174349686288383|0.5511324165035159|0.3320844128641819 |0.7738486877101489|0.2154915886962553|0.4754997600674299 |0.922780639280355 |0.7136894772661909|0.2277580838165979|0.5926874459847249|0.40311408392226633|0.467830264333843 |0.8330466896984213|0.1893258482389527|0.6320849515511165 |0.7530911056912044 |0.06700254871955424|0.370528597355559 |0.2755437445193154|0.23704391110980128|0.8067400174905822|0.13597793616251852|0.1708888820162453|0.01672725007605702|0.983118121881555  |0.25040195628629924|0.060537253723083384|0.20000530582637488|0.3400572407133511|0.9375689433322597 |0.057039316954370256|0.8053269714347623|0.5247817572228813|0.28419308820527944|0.9798908885194533 |0.31805988175678146|0.7034448027077574|0.5400575751346084|0.25336322371116216|0.9361634546853429|0.6118681368289798|0.6295081549153907 |0.13417468943957422|0.41617137072255794|0.7267230869252035|0.023792726137561115|0.5776157058356362  |0.04884204913195467|0.26728716103441275|0.646680370807925  |0.9782712690657244 |0.16434031314818154|0.20985522381321275|0.24739842475440077 |0.26335189682977334|0.19604841662422068|0.10742950487300651|0.20283136488091502|0.3100312319723688|0.886959006630645 |0.25157102269776244|0.34428775168410786|0.3500506818575777|0.3781142441912052 |0.8560316444386715|0.4737104888956839|0.735903101602148|0.02236617130529006|0.8769074095835873 |0.2001426662503153|0.5534032319238532 |0.7289496620397098|0.41955191309992157|0.9337700133660436 |0.34059094378451005|0.6419144759403556|0.08167496930341167|0.9947099478497635|0.48010888605366586|0.22314796858167918|0.17786598882331306|0.7351521162297135 |0.5422057170020095 |0.9521927872726792 |0.7459825486368227 |0.40907708791990627|0.8903819313311575|0.7251413746923618 |0.2977174938745204 |0.9515209660203555|0.9375968604766713|0.5087851740042524|0.4255237544908751 |0.8023768698664653|0.48003189618006703|0.1775841829745185|0.09050775629268382|0.6743909291138167 |0.2498415755876865 |
|0.6866473844170801|0.4774360641212433|0.631696201340726 |0.33979113021468343|0.5663049010847052|0.7280190472258865|0.41370958502324806|0.9977433873622218|0.7671957338989901|0.2788708556233931|0.3355106391656496|0.88478952319287   |0.0333974166999893|0.6061744715862606|0.9617779139652359|0.22484954822341863|0.12770906021550898|0.5577789629508672 |0.2877649024640704|0.5566577406549361|0.9334933255278052 |0.9166720585157266|0.9689249324600591 |0.6367502457478598|0.7993572745928459 |0.23213222324218108|0.11928284054154137|0.6173493362456599  |0.0505122058694798 |0.9050228629552983|0.17112767911121707|0.47395598348370005 |0.5820498657823081|0.6241124650645072|0.18587258258036776|0.14987593554122225|0.3079446253653946 |0.9414228822867968|0.8362276265462365|0.9155655305576353 |0.5121559807153562|0.8963362656525707|0.22765970274318037|0.8177039187132797 |0.8190326635933787 |0.5256005177032199|0.8167598457269669  |0.030936807130934496|0.6733006585281015 |0.4208049626816347 |0.24603085738518538|0.22719198954208153|0.1622280557565281 |0.22217325159218038|0.014684419513742553|0.08987111517447499|0.2157764759142622 |0.8223414104088321 |0.4868624404491777 |0.4016191733088167|0.6169281906889263|0.15603611040433385|0.18289285085714913|0.9538408988218972|0.15037154865295121|0.5364516961987454|0.8077254873163031|0.712600478545675|0.7277477241003857 |0.19822912960348305|0.8305051199208777|0.18631911396566114|0.8909532487898342|0.3470409226992506 |0.35306974180587636|0.9107058868891469 |0.3321327206004986|0.48952332459050607|0.3630403307479373|0.5400046826340376 |0.5387377194310529 |0.42860539421837585|0.23214101630985995|0.21438968839794847|0.15370603160082352|0.04355605642700022|0.6096006707067466 |0.6933354157094292|0.06302172470859002|0.03174631856164001|0.664243581650643 |0.7833239547446621|0.696884598352864 |0.34626385933237736|0.9263495598791336|0.404818892816584  |0.2085585394755507|0.6150004897990109 |0.05391193524302473|0.28188484028329097|
+------------------+------------------+------------------+-------------------+------------------+------------------+-------------------+------------------+------------------+------------------+------------------+-------------------+------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+--------------------+-------------------+------------------+-------------------+--------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+------------------+------------------+-------------------+-------------------+-------------------+------------------+--------------------+--------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+--------------------+-------------------+-------------------+-------------------+-------------------+------------------+------------------+-------------------+-------------------+------------------+-------------------+------------------+------------------+-----------------+-------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+-------------------+------------------+-------------------+-------------------+------------------+------------------+------------------+-------------------+------------------+-------------------+------------------+-------------------+-------------------+-------------------+
only showing top 2 rows
```

`psql`, CLI for PostgreSQL, supports a vertical display mode for this case like:
http://stackoverflow.com/questions/9604723/alternate-output-format-for-psql

```
-RECORD 0-------------------
 c0  | 0.6306087152476858
 c1  | 0.9174349686288383
 c2  | 0.5511324165035159
...
 c98 | 0.05391193524302473
 c99 | 0.28188484028329097
-RECORD 1-------------------
 c0  | 0.6866473844170801
 c1  | 0.4774360641212433
 c2  | 0.631696201340726
...
 c98 | 0.05391193524302473
 c99 | 0.28188484028329097
only showing top 2 rows
```

## How was this patch tested?
Added tests in `DataFrameSuite`.

Author: Takeshi Yamamuro <yamamuro@apache.org>

Closes #17733 from maropu/SPARK-20425.

## What changes were proposed in this pull request?
Some PySpark & SparkR tests run with tiny dataset and tiny ```maxIter```, which means they are not converged. I don’t think checking intermediate result during iteration make sense, and these intermediate result may vulnerable and not stable, so we should switch to check the converged result. We hit this issue at #17746 when we upgrade breeze to 0.13.1.

## How was this patch tested?
Existing tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #17757 from yanboliang/flaky-test.

## What changes were proposed in this pull request?

- Add `rollup` and `cube` methods and corresponding generics.
- Add short description to the vignette.

## How was this patch tested?

- Existing unit tests.
- Additional unit tests covering new features.
- `check-cran.sh`.

Author: zero323 <zero323@users.noreply.github.com>

Closes #17728 from zero323/SPARK-20437.

## What changes were proposed in this pull request?
Upgrade breeze version to 0.13.1, which fixed some critical bugs of L-BFGS-B.

## How was this patch tested?
Existing unit tests.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #17746 from yanboliang/spark-20449.

## What changes were proposed in this pull request?

Add wrappers for `o.a.s.sql.functions`:

- `split` as `split_string`
- `repeat` as `repeat_string`

## How was this patch tested?

Existing tests, additional unit tests, `check-cran.sh`

Author: zero323 <zero323@users.noreply.github.com>

Closes #17729 from zero323/SPARK-20438.

## What changes were proposed in this pull request?

Adds wrappers for `collect_list` and `collect_set`.

## How was this patch tested?

Unit tests, `check-cran.sh`

Author: zero323 <zero323@users.noreply.github.com>

Closes #17672 from zero323/SPARK-20371.

## What changes were proposed in this pull request?

Adds wrappers for `o.a.s.sql.functions.array` and `o.a.s.sql.functions.map`

## How was this patch tested?

Unit tests, `check-cran.sh`

Author: zero323 <zero323@users.noreply.github.com>

Closes #17674 from zero323/SPARK-20375.

## What changes were proposed in this pull request?

Checking a source parameter is asynchronous. When the query is created, it's not guaranteed that source has been created. This PR just increases the timeout of awaitTermination to ensure the parsing error is thrown.

## How was this patch tested?

Jenkins

Author: Shixiong Zhu <shixiong@databricks.com>

Closes #17687 from zsxwing/SPARK-20397.

## What changes were proposed in this pull request?

Document  fpGrowth in:

- vignettes
- programming guide
- code example

## How was this patch tested?

Manual tests.

Author: zero323 <zero323@users.noreply.github.com>

Closes #17557 from zero323/SPARK-20208.

## What changes were proposed in this pull request?

This was suggested to be `as.json.array` at the first place in the PR to SPARK-19828 but we could not do this as the lint check emits an error for multiple dots in the variable names.

After SPARK-20278, now we are able to use `multiple.dots.in.names`. `asJsonArray` in `from_json` function is still able to be changed as 2.2 is not released yet.

So, this PR proposes to rename `asJsonArray` to `as.json.array`.

## How was this patch tested?

Jenkins tests, local tests with `./R/run-tests.sh` and manual `./dev/lint-r`. Existing tests should cover this.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17653 from HyukjinKwon/SPARK-19828-followup.

## What changes were proposed in this pull request?

Currently, multi-dot separated variables in R is not allowed. For example,

```diff
 setMethod("from_json", signature(x = "Column", schema = "structType"),
-          function(x, schema, asJsonArray = FALSE, ...) {
+          function(x, schema, as.json.array = FALSE, ...) {
             if (asJsonArray) {
               jschema <- callJStatic("org.apache.spark.sql.types.DataTypes",
                                      "createArrayType",
```

produces an error as below:

```
R/functions.R:2462:31: style: Words within variable and function names should be separated by '_' rather than '.'.
          function(x, schema, as.json.array = FALSE, ...) {
                              ^~~~~~~~~~~~~
```

This seems against https://google.github.io/styleguide/Rguide.xml#identifiers which says

> The preferred form for variable names is all lower case letters and words separated with dots

This looks because lintr by default https://github.com/jimhester/lintr follows http://r-pkgs.had.co.nz/style.html as written in the README.md. Few cases seems not following Google's one as "a few tweaks".

Per [SPARK-6813](https://issues.apache.org/jira/browse/SPARK-6813), we follow Google's R Style Guide with few exceptions https://google.github.io/styleguide/Rguide.xml. This is also merged into Spark's website - https://github.com/apache/spark-website/pull/43

Also, it looks we have no limit on function name. This rule also looks affecting to the name of functions as written in the README.md.

> `multiple_dots_linter`: check that function and variable names are separated by _ rather than ..

## How was this patch tested?

Manually tested `./dev/lint-r`with the manual change below in `R/functions.R`:

```diff
 setMethod("from_json", signature(x = "Column", schema = "structType"),
-          function(x, schema, asJsonArray = FALSE, ...) {
+          function(x, schema, as.json.array = FALSE, ...) {
             if (asJsonArray) {
               jschema <- callJStatic("org.apache.spark.sql.types.DataTypes",
                                      "createArrayType",
```

**Before**

```R
R/functions.R:2462:31: style: Words within variable and function names should be separated by '_' rather than '.'.
          function(x, schema, as.json.array = FALSE, ...) {
                              ^~~~~~~~~~~~~
```

**After**

```
lintr checks passed.
```

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17590 from HyukjinKwon/disable-dot-in-name.

## What changes were proposed in this pull request?

Fixed spelling of "charactor"

## How was this patch tested?

Spelling change only

Author: Brendan Dwyer <brendan.dwyer@ibm.com>

Closes #17611 from bdwyer2/SPARK-20298.

## What changes were proposed in this pull request?

Test failed because SPARK_HOME is not set before Spark is installed.

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17516 from felixcheung/rdircheckincran.

## What changes were proposed in this pull request?

Following up on #17483, add createTable (which is new in 2.2.0) and deprecate createExternalTable, plus a number of minor fixes

## How was this patch tested?

manual, unit tests

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17511 from felixcheung/rceatetable.

[SPARK-20196][PYTHON][SQL] update doc for catalog functions for all languages, add pyspark refreshByPath API

## What changes were proposed in this pull request?

Update doc to remove external for createTable, add refreshByPath in python

## How was this patch tested?

manual

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17512 from felixcheung/catalogdoc.

## What changes were proposed in this pull request?

minor update

zero323

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17526 from felixcheung/rfpgrowthfollowup.

## What changes were proposed in this pull request?

It seems cran check scripts corrects `R/pkg/DESCRIPTION` and follows the order in `Collate` fields.

This PR proposes to fix `catalog.R`'s order so that running this script does not show up a small diff in this file every time.

## How was this patch tested?

Manually via `./R/check-cran.sh`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17528 from HyukjinKwon/minor-reorder-description.

## What changes were proposed in this pull request?

Adds SparkR API for FPGrowth: [SPARK-19825](https://issues.apache.org/jira/browse/SPARK-19825):

- `spark.fpGrowth` -model training.
- `freqItemsets` and `associationRules` methods with new corresponding generics.
- Scala helper: `org.apache.spark.ml.r. FPGrowthWrapper`
- unit tests.

## How was this patch tested?

Feature specific unit tests.

Author: zero323 <zero323@users.noreply.github.com>

Closes #17170 from zero323/SPARK-19825.

## What changes were proposed in this pull request?

Add a set of catalog API in R

```
"currentDatabase",
"listColumns",
"listDatabases",
"listFunctions",
"listTables",
"recoverPartitions",
"refreshByPath",
"refreshTable",
"setCurrentDatabase",
```
https://github.com/apache/spark/pull/17483/files#diff-6929e6c5e59017ff954e110df20ed7ff

## How was this patch tested?

manual tests, unit tests

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17483 from felixcheung/rcatalog.

JIRA Issue: https://issues.apache.org/jira/browse/SPARK-20123

## What changes were proposed in this pull request?

If $SPARK_HOME or $FWDIR variable contains spaces, then use "./dev/make-distribution.sh --name custom-spark --tgz -Psparkr -Phadoop-2.7 -Phive -Phive-thriftserver -Pmesos -Pyarn" build spark will failed.

## How was this patch tested?

manual tests

Author: zuotingbing <zuo.tingbing9@zte.com.cn>

Closes #17452 from zuotingbing/spark-bulid.

## What changes were proposed in this pull request?

It seems `checkType` and the type string in `structField` are not being tested closely. This string format currently seems SparkR-specific (see https://github.com/apache/spark/blob/d1f6c64c4b763c05d6d79ae5497f298dc3835f3e/sql/core/src/main/scala/org/apache/spark/sql/api/r/SQLUtils.scala#L93-L131) but resembles SQL type definition.

Therefore, it seems nicer if we test positive/negative cases in R side.

## How was this patch tested?

Unit tests in `test_sparkSQL.R`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17439 from HyukjinKwon/r-typestring-tests.

## What changes were proposed in this pull request?

This PR proposes to match minor documentations changes in https://github.com/apache/spark/pull/17399 and https://github.com/apache/spark/pull/17380 to R/Python.

## How was this patch tested?

Manual tests in Python , Python tests via `./python/run-tests.py --module=pyspark-sql` and lint-checks for Python/R.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17429 from HyukjinKwon/minor-match-doc.

## What changes were proposed in this pull request?
SparkR ```spark.getSparkFiles``` fails when it was called on executors, see details at [SPARK-19925](https://issues.apache.org/jira/browse/SPARK-19925).

## How was this patch tested?
Add unit tests, and verify this fix at standalone and yarn cluster.

Author: Yanbo Liang <ybliang8@gmail.com>

Closes #17274 from yanboliang/spark-19925.

## What changes were proposed in this pull request?

When SparkR is installed as a R package there might not be any java runtime.
If it is not there SparkR's `sparkR.session()` will block waiting for the connection timeout, hanging the R IDE/shell, without any notification or message.

## How was this patch tested?

manually

- [x] need to test on Windows

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #16596 from felixcheung/rcheckjava.

## What changes were proposed in this pull request?
Update docs for NaN handling in approxQuantile.

## How was this patch tested?
existing tests.

Author: Zheng RuiFeng <ruifengz@foxmail.com>

Closes #17369 from zhengruifeng/doc_quantiles_nan.

## What changes were proposed in this pull request?

Currently JSON and CSV have exactly the same logic about handling bad records, this PR tries to abstract it and put it in a upper level to reduce code duplication.

The overall idea is, we make the JSON and CSV parser to throw a BadRecordException, then the upper level, FailureSafeParser, handles bad records according to the parse mode.

Behavior changes:
1. with PERMISSIVE mode, if the number of tokens doesn't match the schema, previously CSV parser will treat it as a legal record and parse as many tokens as possible. After this PR, we treat it as an illegal record, and put the raw record string in a special column, but we still parse as many tokens as possible.
2. all logging is removed as they are not very useful in practice.

## How was this patch tested?

existing tests

Author: Wenchen Fan <wenchen@databricks.com>
Author: hyukjinkwon <gurwls223@gmail.com>
Author: Wenchen Fan <cloud0fan@gmail.com>

Closes #17315 from cloud-fan/bad-record2.

## What changes were proposed in this pull request?

doc only change

## How was this patch tested?

manual

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17356 from felixcheung/rdfcheckpoint2.

## What changes were proposed in this pull request?

Add checkpoint, setCheckpointDir API to R

## How was this patch tested?

unit tests, manual tests

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17351 from felixcheung/rdfcheckpoint.

## What changes were proposed in this pull request?

This PR proposes to support an array of struct type in `to_json` as below:

```scala
import org.apache.spark.sql.functions._

val df = Seq(Tuple1(Tuple1(1) :: Nil)).toDF("a")
df.select(to_json($"a").as("json")).show()
```

```
+----------+
|      json|
+----------+
|[{"_1":1}]|
+----------+
```

Currently, it throws an exception as below (a newline manually inserted for readability):

```
org.apache.spark.sql.AnalysisException: cannot resolve 'structtojson(`array`)' due to data type
mismatch: structtojson requires that the expression is a struct expression.;;
```

This allows the roundtrip with `from_json` as below:

```scala
import org.apache.spark.sql.functions._
import org.apache.spark.sql.types._

val schema = ArrayType(StructType(StructField("a", IntegerType) :: Nil))
val df = Seq("""[{"a":1}, {"a":2}]""").toDF("json").select(from_json($"json", schema).as("array"))
df.show()

// Read back.
df.select(to_json($"array").as("json")).show()
```

```
+----------+
|     array|
+----------+
|[[1], [2]]|
+----------+

+-----------------+
|             json|
+-----------------+
|[{"a":1},{"a":2}]|
+-----------------+
```

Also, this PR proposes to rename from `StructToJson` to `StructsToJson ` and `JsonToStruct` to `JsonToStructs`.

## How was this patch tested?

Unit tests in `JsonFunctionsSuite` and `JsonExpressionsSuite` for Scala, doctest for Python and test in `test_sparkSQL.R` for R.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17192 from HyukjinKwon/SPARK-19849.

## What changes were proposed in this pull request?

Passes R `tempdir()` (this is the R session temp dir, shared with other temp files/dirs) to JVM, set System.Property for derby home dir to move derby.log

## How was this patch tested?

Manually, unit tests

With this, these are relocated to under /tmp
```
# ls /tmp/RtmpG2M0cB/
derby.log
```
And they are removed automatically when the R session is ended.

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #16330 from felixcheung/rderby.

## What changes were proposed in this pull request?

It seems cran check scripts corrects `R/pkg/DESCRIPTION` and follows the order in `Collate` fields.

This PR proposes to fix this so that running this script does not show up a diff in this file.

## How was this patch tested?

Manually via `./R/check-cran.sh`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17349 from HyukjinKwon/minor-cran.

## What changes were proposed in this pull request?

Add "experimental" API for SS in R

## How was this patch tested?

manual, unit tests

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #16982 from felixcheung/rss.

## What changes were proposed in this pull request?

Since we could not directly define the array type in R, this PR proposes to support array types in R as string types that are used in `structField` as below:

```R
jsonArr <- "[{\"name\":\"Bob\"}, {\"name\":\"Alice\"}]"
df <- as.DataFrame(list(list("people" = jsonArr)))
collect(select(df, alias(from_json(df$people, "array<struct<name:string>>"), "arrcol")))
```

prints

```R
      arrcol
1 Bob, Alice
```

## How was this patch tested?

Unit tests in `test_sparkSQL.R`.

Author: hyukjinkwon <gurwls223@gmail.com>

Closes #17178 from HyukjinKwon/SPARK-19828.

## What changes were proposed in this pull request?
Port Tweedie GLM  #16344  to SparkR

felixcheung yanboliang

## How was this patch tested?
new test in SparkR

Author: actuaryzhang <actuaryzhang10@gmail.com>

Closes #16729 from actuaryzhang/sparkRTweedie.

## What changes were proposed in this pull request?

RandomForest R Wrapper and GBT R Wrapper return param `maxDepth` to R models.

Below 4 R wrappers are changed:
* `RandomForestClassificationWrapper`
* `RandomForestRegressionWrapper`
* `GBTClassificationWrapper`
* `GBTRegressionWrapper`

## How was this patch tested?

Test manually on my local machine.

Author: Xin Ren <iamshrek@126.com>

Closes #17207 from keypointt/SPARK-19282.

### What changes were proposed in this pull request?

Observed by felixcheung  in https://github.com/apache/spark/pull/16739, when users use the shuffle-enabled `repartition` API, they expect the partition they got should be the exact number they provided, even if they call shuffle-disabled `coalesce` later.

Currently, `CollapseRepartition` rule does not consider whether shuffle is enabled or not. Thus, we got the following unexpected result.

```Scala
    val df = spark.range(0, 10000, 1, 5)
    val df2 = df.repartition(10)
    assert(df2.coalesce(13).rdd.getNumPartitions == 5)
    assert(df2.coalesce(7).rdd.getNumPartitions == 5)
    assert(df2.coalesce(3).rdd.getNumPartitions == 3)
```

This PR is to fix the issue. We preserve shuffle-enabled Repartition.

### How was this patch tested?
Added a test case

Author: Xiao Li <gatorsmile@gmail.com>

Closes #16933 from gatorsmile/CollapseRepartition.

## What changes were proposed in this pull request?
Added checks for name consistency of input data frames in union.

## How was this patch tested?
new test.

Author: actuaryzhang <actuaryzhang10@gmail.com>

Closes #17159 from actuaryzhang/sparkRUnion.

## What changes were proposed in this pull request?

Add column functions: to_json, from_json, and tests covering error cases.

## How was this patch tested?

unit tests, manual

Author: Felix Cheung <felixcheung_m@hotmail.com>

Closes #17134 from felixcheung/rtojson.

## What changes were proposed in this pull request?

Update R document to use JDK8.

## How was this patch tested?

manual tests

Author: Yuming Wang <wgyumg@gmail.com>

Closes #17162 from wangyum/SPARK-19550.