Use `dropFactors` column-wise instead of nested loop when `createDataFrame` from a `data.frame`

At this moment SparkR createDataFrame is using nested loop to convert factors to character when called on a local data.frame.  It works but is incredibly slow especially with data.table (~ 2 orders of magnitude compared to PySpark / Pandas version on a DateFrame of size 1M rows x 2 columns).

A simple improvement is to apply `dropFactor `column-wise and then reshape output list.

It should at least partially address [SPARK-8277](https://issues.apache.org/jira/browse/SPARK-8277).

Author: zero323 <matthew.szymkiewicz@gmail.com>

Closes #9099 from zero323/SPARK-11086.

switched stddev support from DeclarativeAggregate to ImperativeAggregate.

Author: JihongMa <linlin200605@gmail.com>

Closes #9380 from JihongMA/SPARK-11420.

Checked names, none of them should conflict with anything in base

shivaram davies rxin

Author: felixcheung <felixcheung_m@hotmail.com>

Closes #9489 from felixcheung/rstddev.

This is a follow up on PR #8984, as the corresponding branch for such PR was damaged.

Author: Oscar D. Lara Yejas <olarayej@mail.usf.edu>

Closes #9579 from olarayej/SPARK-10863_NEW14.

Make sample test less flaky by setting the seed

Tested with
```
repeat {  if (count(sample(df, FALSE, 0.1)) == 3) { break } }
```

Author: felixcheung <felixcheung_m@hotmail.com>

Closes #9549 from felixcheung/rsample.

https://issues.apache.org/jira/browse/SPARK-10116

This is really trivial, just happened to notice it -- if `XORShiftRandom.hashSeed` is really supposed to have random bits throughout (as the comment implies), it needs to do something for the conversion to `long`.

mengxr mkolod

Author: Imran Rashid <irashid@cloudera.com>

Closes #8314 from squito/SPARK-10116.

Author: adrian555 <wzhuang@us.ibm.com>
Author: Adrian Zhuang <adrian555@users.noreply.github.com>

Closes #9443 from adrian555/with.

Author: Sun Rui <rui.sun@intel.com>

Closes #9196 from sun-rui/SPARK-11210.

Author: Sun Rui <rui.sun@intel.com>

Closes #9193 from sun-rui/SPARK-11209.

Add merge function to DataFrame, which supports R signature.
https://stat.ethz.ch/R-manual/R-devel/library/base/html/merge.html

Author: Narine Kokhlikyan <narine.kokhlikyan@gmail.com>

Closes #9012 from NarineK/sparkrmerge.

This PR introduce a new feature to run SQL directly on files without create a table, for example:

```
select id from json.`path/to/json/files` as j
```

Author: Davies Liu <davies@databricks.com>

Closes #9173 from davies/source.

Author: Sun Rui <rui.sun@intel.com>

Closes #9023 from sun-rui/SPARK-10996.

I was having issues with collect() and orderBy() in Spark 1.5.0 so I used the DataFrame.R file and test_sparkSQL.R file from the Spark 1.5.1 download. I only modified the join() function in DataFrame.R to include "full", "fullouter", "left", "right", and "leftsemi" and added corresponding test cases in the test for join() and merge() in test_sparkSQL.R file.
Pull request because I filed this JIRA bug report:
https://issues.apache.org/jira/browse/SPARK-10981

Author: Monica Liu <liu.monica.f@gmail.com>

Closes #9029 from mfliu/master.

Bring the change code up to date.

Author: Adrian Zhuang <adrian555@users.noreply.github.com>
Author: adrian555 <wzhuang@us.ibm.com>

Closes #9031 from adrian555/attach2.

as.DataFrame is more a R-style like signature.
Also, I'd like to know if we could make the context, e.g. sqlContext global, so that we do not have to specify it as an argument, when we each time create a dataframe.

Author: Narine Kokhlikyan <narine.kokhlikyan@gmail.com>

Closes #8952 from NarineK/sparkrasDataFrame.

Two points in this PR:

1.    Originally thought was that a named R list is assumed to be a struct in SerDe. But this is problematic because some R functions will implicitly generate named lists that are not intended to be a struct when transferred by SerDe. So SerDe clients have to explicitly mark a names list as struct by changing its class from "list" to "struct".

2.    SerDe is in the Spark Core module, and data of StructType is represented as GenricRow which is defined in Spark SQL module. SerDe can't import GenricRow as in maven build  Spark SQL module depends on Spark Core module. So this PR adds a registration hook in SerDe to allow SQLUtils in Spark SQL module to register its functions for serialization and deserialization of StructType.

Author: Sun Rui <rui.sun@intel.com>

Closes #8794 from sun-rui/SPARK-10051.

1.  Add a "col" function into DataFrame.
2.  Move the current "col" function in Column.R to functions.R, convert it to S4 function.
3.  Add a s4 "column" function in functions.R.
4.  Convert the "column" function in Column.R to S4 function. This is for private use.

Author: Sun Rui <rui.sun@intel.com>

Closes #8864 from sun-rui/SPARK-10079.

[SPARK-10905][SparkR]: Export freqItems() for DataFrameStatFunctions
- Add function (together with roxygen2 doc) to DataFrame.R and generics.R
- Expose the function in NAMESPACE
- Add unit test for the function

Author: Rerngvit Yanggratoke <rerngvit@kth.se>

Closes #8962 from rerngvit/SPARK-10905.

the sort function can be used as an alternative to arrange(... ).
As arguments it accepts x - dataframe, decreasing - TRUE/FALSE, a list of orderings for columns and the list of columns, represented as string names

for example:
sort(df, TRUE, "col1","col2","col3","col5") # for example, if we want to sort some of the columns in the same order

sort(df, decreasing=TRUE, "col1")
sort(df, decreasing=c(TRUE,FALSE), "col1","col2")

Author: Narine Kokhlikyan <narine.kokhlikyan@gmail.com>

Closes #8920 from NarineK/sparkrsort.

Author: Sun Rui <rui.sun@intel.com>

Closes #8869 from sun-rui/SPARK-10752.

The fix is to coerce `c("a", "b")` into a list such that it could be serialized to call JVM with.

Author: felixcheung <felixcheung_m@hotmail.com>

Closes #8961 from felixcheung/rselect.

Created method as.data.frame as a synonym for collect().

Author: Oscar D. Lara Yejas <olarayej@mail.usf.edu>
Author: olarayej <oscar.lara.yejas@us.ibm.com>
Author: Oscar D. Lara Yejas <oscar.lara.yejas@us.ibm.com>

Closes #8908 from olarayej/SPARK-10807.

1. Support collecting data of MapType from DataFrame.
2. Support data of MapType in createDataFrame.

Author: Sun Rui <rui.sun@intel.com>

Closes #8711 from sun-rui/SPARK-10050.

Adding STDDEV support for DataFrame using 1-pass online /parallel algorithm to compute variance. Please review the code change.

Author: JihongMa <linlin200605@gmail.com>
Author: Jihong MA <linlin200605@gmail.com>
Author: Jihong MA <jihongma@jihongs-mbp.usca.ibm.com>
Author: Jihong MA <jihongma@Jihongs-MacBook-Pro.local>

Closes #6297 from JihongMA/SPARK-SQL.

this PR :
1.  Enhance reflection in RBackend. Automatically matching a Java array to Scala Seq when finding methods. Util functions like seq(), listToSeq() in R side can be removed, as they will conflict with the Serde logic that transferrs a Scala seq to R side.

2.  Enhance the SerDe to support transferring  a Scala seq to R side. Data of ArrayType in DataFrame
after collection is observed to be of Scala Seq type.

3.  Support ArrayType in createDataFrame().

Author: Sun Rui <rui.sun@intel.com>

Closes #8458 from sun-rui/SPARK-10049.

Spark gives an error message and does not show the output when a field of the result DataFrame contains characters in CJK.
I changed SerDe.scala in order that Spark support Unicode characters when writes a string to R.

Author: CHOIJAEHONG <redrock07@naver.com>

Closes #7494 from CHOIJAEHONG1/SPARK-8951.

Add subset and transform
Also reorganize `[` & `[[` to subset instead of select

Note: for transform, transform is very similar to mutate. Spark doesn't seem to replace existing column with the name in mutate (ie. `mutate(df, age = df$age + 2)` - returned DataFrame has 2 columns with the same name 'age'), so therefore not doing that for now in transform.
Though it is clearly stated it should replace column with matching name (should I open a JIRA for mutate/transform?)

Author: felixcheung <felixcheung_m@hotmail.com>

Closes #8503 from felixcheung/rsubset_transform.

S3 function is at https://stat.ethz.ch/R-manual/R-patched/library/stats/html/na.fail.html

Author: Shivaram Venkataraman <shivaram@cs.berkeley.edu>
Author: Shivaram Venkataraman <shivaram.venkataraman@gmail.com>
Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8495 from shivaram/na-omit-fix.

cc sun-rui davies

Author: Shivaram Venkataraman <shivaram@cs.berkeley.edu>

Closes #8475 from shivaram/varargs-fix.

Getting rid of some validation problems in SparkR
https://github.com/apache/spark/pull/7883

cc shivaram

```
inst/tests/test_Serde.R:26:1: style: Trailing whitespace is superfluous.

^~
inst/tests/test_Serde.R:34:1: style: Trailing whitespace is superfluous.

^~
inst/tests/test_Serde.R:37:38: style: Trailing whitespace is superfluous.
  expect_equal(class(x), "character")
                                     ^~
inst/tests/test_Serde.R:50:1: style: Trailing whitespace is superfluous.

^~
inst/tests/test_Serde.R:55:1: style: Trailing whitespace is superfluous.

^~
inst/tests/test_Serde.R:60:1: style: Trailing whitespace is superfluous.

^~
inst/tests/test_sparkSQL.R:611:1: style: Trailing whitespace is superfluous.

^~
R/DataFrame.R:664:1: style: Trailing whitespace is superfluous.

^~~~~~~~~~~~~~
R/DataFrame.R:670:55: style: Trailing whitespace is superfluous.
                df <- data.frame(row.names = 1 : nrow)
                                                      ^~~~~~~~~~~~~~~~
R/DataFrame.R:672:1: style: Trailing whitespace is superfluous.

^~~~~~~~~~~~~~
R/DataFrame.R:686:49: style: Trailing whitespace is superfluous.
                    df[[names[colIndex]]] <- vec
                                                ^~~~~~~~~~~~~~~~~~
```

Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8474 from yu-iskw/minor-fix-sparkr.

Add support for
```
   df[df$name == "Smith", c(1,2)]
   df[df$age %in% c(19, 30), 1:2]
```

shivaram

Author: felixcheung <felixcheung_m@hotmail.com>

Closes #8394 from felixcheung/rsubset.

### JIRA
[[SPARK-10106] Add `ifelse` Column function to SparkR - ASF JIRA](https://issues.apache.org/jira/browse/SPARK-10106)

Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8303 from yu-iskw/SPARK-10106.

I added lots of Column functinos into SparkR. And I also added `rand(seed: Int)` and `randn(seed: Int)` in Scala. Since we need such APIs for R integer type.

### JIRA
[[SPARK-9856] Add expression functions into SparkR whose params are complicated - ASF JIRA](https://issues.apache.org/jira/browse/SPARK-9856)

Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8264 from yu-iskw/SPARK-9856-3.

- Add `when` and `otherwise` as `Column` methods
- Add `When` as an expression function
- Add `%otherwise%` infix as an alias of `otherwise`

Since R doesn't support a feature like method chaining, `otherwise(when(condition, value), value)` style is a little annoying for me. If `%otherwise%` looks strange for shivaram, I can remove it. What do you think?

### JIRA
[[SPARK-10075] Add `when` expressino function in SparkR - ASF JIRA](https://issues.apache.org/jira/browse/SPARK-10075)

Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8266 from yu-iskw/SPARK-10075.

### Summary

- Add `lit` function
- Add `concat`, `greatest`, `least` functions

I think we need to improve `collect` function in order to implement `struct` function. Since `collect` doesn't work with arguments which includes a nested `list` variable. It seems that a list against `struct` still has `jobj` classes. So it would be better to solve this problem on another issue.

### JIRA
[[SPARK-9871] Add expression functions into SparkR which have a variable parameter - ASF JIRA](https://issues.apache.org/jira/browse/SPARK-9871)

Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8194 from yu-iskw/SPARK-9856.

This is a WIP patch for SPARK-8844  for collecting reviews.

This bug is about reading an empty DataFrame. in readCol(),
      lapply(1:numRows, function(x) {
does not take into consideration the case where numRows = 0.

Will add unit test case.

Author: Sun Rui <rui.sun@intel.com>

Closes #7419 from sun-rui/SPARK-8844.

I added lots of expression functions for SparkR. This PR includes only functions whose params  are only `(Column)` or `(Column, Column)`.  And I think we need to improve how to test those functions. However, it would be better to work on another issue.

## Diff Summary

- Add lots of functions in `functions.R` and their generic in `generic.R`
- Add aliases for `ceiling` and `sign`
- Move expression functions from `column.R` to `functions.R`
- Modify `rdname` from `column` to `functions`

I haven't supported `not` function, because the name has a collesion with `testthat` package. I didn't think of the way  to define it.

## New Supported Functions

```
approxCountDistinct
ascii
base64
bin
bitwiseNOT
ceil (alias: ceiling)
crc32
dayofmonth
dayofyear
explode
factorial
hex
hour
initcap
isNaN
last_day
length
log2
ltrim
md5
minute
month
negate
quarter
reverse
round
rtrim
second
sha1
signum (alias: sign)
size
soundex
to_date
trim
unbase64
unhex
weekofyear
year

datediff
levenshtein
months_between
nanvl
pmod
```

## JIRA
[[SPARK-9855] Add expression functions into SparkR whose params are simple - ASF JIRA](https://issues.apache.org/jira/browse/SPARK-9855)

Author: Yu ISHIKAWA <yuu.ishikawa@gmail.com>

Closes #8123 from yu-iskw/SPARK-9855.

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

Adds following aliases:
* unique (distinct)
* rbind (unionAll): accepts many DataFrames
* nrow (count)
* ncol
* dim
* names (columns): along with the replacement function to change names

Author: Hossein <hossein@databricks.com>

Closes #7764 from falaki/sparkR-alias and squashes the following commits:

56016f5 [Hossein] Updated R documentation
5e4a4d0 [Hossein] Removed extra code
f51cbef [Hossein] Merge branch 'master' into sparkR-alias
c1b88bd [Hossein] Moved setGeneric and other comments applied
d9307f8 [Hossein] Added tests
b5aa988 [Hossein] Added dim, ncol, nrow, names, rbind, and unique functions to DataFrames

With the change in this patch, I get no more warnings from `./dev/lint-r` in my machine

Author: Shivaram Venkataraman <shivaram@cs.berkeley.edu>

Closes #7834 from shivaram/sparkr-style-fixes and squashes the following commits:

716cd8e [Shivaram Venkataraman] Remaining SparkR style fixes