If pandas is broken (can't be imported, raise other exceptions other than ImportError), pyspark can't be imported, we should ignore all the exceptions.

Author: Davies Liu <davies@databricks.com>

Closes #8173 from davies/fix_pandas.

Author: Reynold Xin <rxin@databricks.com>

Closes #8138 from rxin/SPARK-9907.

rxin

First pull request for Spark so let me know if I am missing anything
The contribution is my original work and I license the work to the project under the project's open source license.

Author: Brennan Ashton <bashton@brennanashton.com>

Closes #8016 from btashton/patch-1.

Raise an read-only exception when user try to mutable a Row.

Author: Davies Liu <davies@databricks.com>

Closes #8009 from davies/readonly_row and squashes the following commits:

8722f3f [Davies Liu] add tests
05a3d36 [Davies Liu] Row should be read-only

Add an option `recursive` to `Row.asDict()`, when True (default is False), it will convert the nested Row into dict.

Author: Davies Liu <davies@databricks.com>

Closes #8006 from davies/as_dict and squashes the following commits:

922cc5a [Davies Liu] turn Row into dict recursively

All data sources show up as "PhysicalRDD" in physical plan explain. It'd be better if we can show the name of the data source.

Without this patch:
```
== Physical Plan ==
NewAggregate with UnsafeHybridAggregationIterator ArrayBuffer(date#0, cat#1) ArrayBuffer((sum(CAST((CAST(count#2, IntegerType) + 1), LongType))2,mode=Final,isDistinct=false))
 Exchange hashpartitioning(date#0,cat#1)
  NewAggregate with UnsafeHybridAggregationIterator ArrayBuffer(date#0, cat#1) ArrayBuffer((sum(CAST((CAST(count#2, IntegerType) + 1), LongType))2,mode=Partial,isDistinct=false))
   PhysicalRDD [date#0,cat#1,count#2], MapPartitionsRDD[3] at
```

With this patch:
```
== Physical Plan ==
TungstenAggregate(key=[date#0,cat#1], value=[(sum(CAST((CAST(count#2, IntegerType) + 1), LongType)),mode=Final,isDistinct=false)]
 Exchange hashpartitioning(date#0,cat#1)
  TungstenAggregate(key=[date#0,cat#1], value=[(sum(CAST((CAST(count#2, IntegerType) + 1), LongType)),mode=Partial,isDistinct=false)]
   ConvertToUnsafe
    Scan ParquetRelation[file:/scratch/rxin/spark/sales4][date#0,cat#1,count#2]
```

Author: Reynold Xin <rxin@databricks.com>

Closes #8024 from rxin/SPARK-9733 and squashes the following commits:

811b90e [Reynold Xin] Fixed Python test case.
52cab77 [Reynold Xin] Cast.
eea9ccc [Reynold Xin] Fix test case.
fcecb22 [Reynold Xin] [SPARK-9733][SQL] Improve explain message for data source scan node.

https://issues.apache.org/jira/browse/SPARK-9691

jkbradley rxin

Author: Yin Huai <yhuai@databricks.com>

Closes #7999 from yhuai/pythonRand and squashes the following commits:

4187e0c [Yin Huai] Regression test.
a985ef9 [Yin Huai] Use "if seed is not None" instead "if seed" because "if seed" returns false when seed is 0.

Inspiration drawn from this blog post: https://lab.getbase.com/pandarize-spark-dataframes/

Author: Reynold Xin <rxin@databricks.com>

Closes #7977 from rxin/isin and squashes the following commits:

9b1d3d6 [Reynold Xin] Added return.
2197d37 [Reynold Xin] Fixed test case.
7c1b6cf [Reynold Xin] Import warnings.
4f4a35d [Reynold Xin] [SPARK-9659][SQL] Rename inSet to isin to match Pandas function.

![translate](http://www.w3resource.com/PostgreSQL/postgresql-translate-function.png)

Author: zhichao.li <zhichao.li@intel.com>

Closes #7709 from zhichao-li/translate and squashes the following commits:

9418088 [zhichao.li] refine checking condition
f2ab77a [zhichao.li] clone string
9d88f2d [zhichao.li] fix indent
6aa2962 [zhichao.li] style
e575ead [zhichao.li] add python api
9d4bab0 [zhichao.li] add special case for fodable and refactor unittest
eda7ad6 [zhichao.li] update to use TernaryExpression
cdfd4be [zhichao.li] add function translate

JIRA: https://issues.apache.org/jira/browse/SPARK-6591

Author: Yijie Shen <henry.yijieshen@gmail.com>

Closes #7926 from yjshen/py_dsload_opt and squashes the following commits:

b207832 [Yijie Shen] fix style
efdf834 [Yijie Shen] resolve comment
7a8f6a2 [Yijie Shen] lowercase
822e769 [Yijie Shen] convert load opts to string

This PR is based on #7580 , thanks to EntilZha

PR for work on https://issues.apache.org/jira/browse/SPARK-8231

Currently, I have an initial implementation for contains. Based on discussion on JIRA, it should behave same as Hive: https://github.com/apache/hive/blob/master/ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDFArrayContains.java#L102-L128

Main points are:
1. If the array is empty, null, or the value is null, return false
2. If there is a type mismatch, throw error
3. If comparison is not supported, throw error

Closes #7580

Author: Pedro Rodriguez <prodriguez@trulia.com>
Author: Pedro Rodriguez <ski.rodriguez@gmail.com>
Author: Davies Liu <davies@databricks.com>

Closes #7949 from davies/array_contains and squashes the following commits:

d3c08bc [Davies Liu] use foreach() to avoid copy
bc3d1fe [Davies Liu] fix array_contains
719e37d [Davies Liu] Merge branch 'master' of github.com:apache/spark into array_contains
e352cf9 [Pedro Rodriguez] fixed diff from master
4d5b0ff [Pedro Rodriguez] added docs and another type check
ffc0591 [Pedro Rodriguez] fixed unit test
7a22deb [Pedro Rodriguez] Changed test to use strings instead of long/ints which are different between python 2 an 3
b5ffae8 [Pedro Rodriguez] fixed pyspark test
4e7dce3 [Pedro Rodriguez] added more docs
3082399 [Pedro Rodriguez] fixed unit test
46f9789 [Pedro Rodriguez] reverted change
d3ca013 [Pedro Rodriguez] Fixed type checking to match hive behavior, then added tests to insure this
8528027 [Pedro Rodriguez] added more tests
686e029 [Pedro Rodriguez] fix scala style
d262e9d [Pedro Rodriguez] reworked type checking code and added more tests
2517a58 [Pedro Rodriguez] removed unused import
28b4f71 [Pedro Rodriguez] fixed bug with type conversions and re-added tests
12f8795 [Pedro Rodriguez] fix scala style checks
e8a20a9 [Pedro Rodriguez] added python df (broken atm)
65b562c [Pedro Rodriguez] made array_contains nullable false
33b45aa [Pedro Rodriguez] reordered test
9623c64 [Pedro Rodriguez] fixed test
4b4425b [Pedro Rodriguez] changed Arrays in tests to Seqs
72cb4b1 [Pedro Rodriguez] added checkInputTypes and docs
69c46fb [Pedro Rodriguez] added tests and codegen
9e0bfc4 [Pedro Rodriguez] initial attempt at implementation

This adds Python API for those DataFrame functions that is introduced in 1.5.

There is issue with serialize byte_array in Python 3, so some of functions (for BinaryType) does not have tests.

cc rxin

Author: Davies Liu <davies@databricks.com>

Closes #7922 from davies/python_functions and squashes the following commits:

8ad942f [Davies Liu] fix test
5fb6ec3 [Davies Liu] fix bugs
3495ed3 [Davies Liu] fix issues
ea5f7bb [Davies Liu] Add python API for DataFrame functions

This PR is based on #7208 , thanks to HuJiayin

Closes #7208

Author: HuJiayin <jiayin.hu@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #7850 from davies/initcap and squashes the following commits:

54472e9 [Davies Liu] fix python test
17ffe51 [Davies Liu] Merge branch 'master' of github.com:apache/spark into initcap
ca46390 [Davies Liu] Merge branch 'master' of github.com:apache/spark into initcap
3a906e4 [Davies Liu] implement title case in UTF8String
8b2506a [HuJiayin] Update functions.py
2cd43e5 [HuJiayin] fix python style check
b616c0e [HuJiayin] add python api
1f5a0ef [HuJiayin] add codegen
7e0c604 [HuJiayin] Merge branch 'master' of https://github.com/apache/spark into initcap
6a0b958 [HuJiayin] add column
c79482d [HuJiayin] support soundex
7ce416b [HuJiayin] support initcap rebase code

This is based on #7641, thanks to zhichao-li

Closes #7641

Author: zhichao.li <zhichao.li@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #7848 from davies/substr and squashes the following commits:

461b709 [Davies Liu] remove bytearry from tests
b45377a [Davies Liu] Merge branch 'master' of github.com:apache/spark into substr
01d795e [zhichao.li] scala style
99aa130 [zhichao.li] add substring to dataframe
4f68bfe [zhichao.li] add binary type support for substring

This PR is based on #7581 , just fix the conflict.

Author: Cheng Hao <hao.cheng@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #7851 from davies/sort_array and squashes the following commits:

a80ef66 [Davies Liu] fix conflict
7cfda65 [Davies Liu] Merge branch 'master' of github.com:apache/spark into sort_array
664c960 [Cheng Hao] update the sort_array by using the ArrayData
276d2d5 [Cheng Hao] add empty line
0edab9c [Cheng Hao] Add asending/descending support for sort_array
80fc0f8 [Cheng Hao] Add type checking
a42b678 [Cheng Hao] Add sort_array support

This reverts commit 67ad4e21.

Add expression `sort_array` support.

Author: Cheng Hao <hao.cheng@intel.com>

This patch had conflicts when merged, resolved by
Committer: Davies Liu <davies.liu@gmail.com>

Closes #7581 from chenghao-intel/sort_array and squashes the following commits:

664c960 [Cheng Hao] update the sort_array by using the ArrayData
276d2d5 [Cheng Hao] add empty line
0edab9c [Cheng Hao] Add asending/descending support for sort_array
80fc0f8 [Cheng Hao] Add type checking
a42b678 [Cheng Hao] Add sort_array support

This PR is based on #7533 , thanks to zhichao-li

Closes #7533

Author: zhichao.li <zhichao.li@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #7843 from davies/str_index and squashes the following commits:

391347b [Davies Liu] add python api
3ce7802 [Davies Liu] fix substringIndex
f2d29a1 [Davies Liu] Merge branch 'master' of github.com:apache/spark into str_index
515519b [zhichao.li] add foldable and remove null checking
9546991 [zhichao.li] scala style
67c253a [zhichao.li] hide some apis and clean code
b19b013 [zhichao.li] add codegen and clean code
ac863e9 [zhichao.li] reduce the calling of numChars
12e108f [zhichao.li] refine unittest
d92951b [zhichao.li] add lastIndexOf
52d7b03 [zhichao.li] add substring_index function

This PR brings SQL function soundex(), see https://issues.apache.org/jira/browse/HIVE-9738

It's based on #7115 , thanks to HuJiayin

Author: HuJiayin <jiayin.hu@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #7812 from davies/soundex and squashes the following commits:

fa75941 [Davies Liu] Merge branch 'master' of github.com:apache/spark into soundex
a4bd6d8 [Davies Liu] fix soundex
2538908 [HuJiayin] add codegen soundex
d15d329 [HuJiayin] add back ut
ded1a14 [HuJiayin] Merge branch 'master' of https://github.com/apache/spark
e2dec2c [HuJiayin] support soundex rebase code

This PR is based on #6988 , thanks to adrian-wang .

This brings two SQL functions: to_date() and trunc().

Closes #6988

Author: Daoyuan Wang <daoyuan.wang@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #7805 from davies/to_date and squashes the following commits:

2c7beba [Davies Liu] Merge branch 'master' of github.com:apache/spark into to_date
310dd55 [Daoyuan Wang] remove dup test in rebase
980b092 [Daoyuan Wang] resolve rebase conflict
a476c5a [Daoyuan Wang] address comments from davies
d44ea5f [Daoyuan Wang] function to_date, trunc

This was previously committed but then reverted due to test failures (see #6769).

Author: Xiangrui Meng <meng@databricks.com>

Closes #7755 from rxin/SPARK-7157 and squashes the following commits:

fbf9044 [Xiangrui Meng] fix python test
542bd37 [Xiangrui Meng] update test
604fe6d [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-7157
f051afd [Xiangrui Meng] use udf instead of building expression
f4e9425 [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-7157
8fb990b [Xiangrui Meng] Merge remote-tracking branch 'apache/master' into SPARK-7157
103beb3 [Xiangrui Meng] add Java-friendly sampleBy
991f26f [Xiangrui Meng] fix seed
4a14834 [Xiangrui Meng] move sampleBy to stat
832f7cc [Xiangrui Meng] add sampleBy to DataFrame

This is based on MechCoder 's PR https://github.com/apache/spark/pull/7731. Hopefully it could pass tests. MechCoder I tried to make minimal changes. If this passes Jenkins, we can merge this one first and then try to move `__init__.py` to `local.py` in a separate PR.

Closes #7731

Author: Xiangrui Meng <meng@databricks.com>

Closes #7746 from mengxr/SPARK-9408 and squashes the following commits:

0e05a3b [Xiangrui Meng] merge master
1135551 [Xiangrui Meng] add a comment for str(...)
c48cae0 [Xiangrui Meng] update tests
173a805 [Xiangrui Meng] move linalg.py to linalg/__init__.py

[SPARK-8186] [SPARK-8187] [SPARK-8194] [SPARK-8198] [SPARK-9133] [SPARK-9290] [SQL] functions: date_add, date_sub, add_months, months_between, time-interval calculation

This PR is based on #7589 , thanks to adrian-wang

Added SQL function date_add, date_sub, add_months, month_between, also add a rule for
add/subtract of date/timestamp and interval.

Closes #7589

cc rxin

Author: Daoyuan Wang <daoyuan.wang@intel.com>
Author: Davies Liu <davies@databricks.com>

Closes #7754 from davies/date_add and squashes the following commits:

e8c633a [Davies Liu] Merge branch 'master' of github.com:apache/spark into date_add
9e8e085 [Davies Liu] Merge branch 'master' of github.com:apache/spark into date_add
6224ce4 [Davies Liu] fix conclict
bd18cd4 [Davies Liu] Merge branch 'master' of github.com:apache/spark into date_add
e47ff2c [Davies Liu] add python api, fix date functions
01943d0 [Davies Liu] Merge branch 'master' into date_add
522e91a [Daoyuan Wang] fix
e8a639a [Daoyuan Wang] fix
42df486 [Daoyuan Wang] fix style
87c4b77 [Daoyuan Wang] function add_months, months_between and some fixes
1a68e03 [Daoyuan Wang] poc of time interval calculation
c506661 [Daoyuan Wang] function date_add , date_sub

Also we could create a Python UDT without having a Scala one, it's important for Python users.

cc mengxr JoshRosen

Author: Davies Liu <davies@databricks.com>

Closes #7453 from davies/class_in_main and squashes the following commits:

4dfd5e1 [Davies Liu] add tests for Python and Scala UDT
793d9b2 [Davies Liu] Merge branch 'master' of github.com:apache/spark into class_in_main
dc65f19 [Davies Liu] address comment
a9a3c40 [Davies Liu] Merge branch 'master' of github.com:apache/spark into class_in_main
a86e1fc [Davies Liu] fix serialization
ad528ba [Davies Liu] Merge branch 'master' of github.com:apache/spark into class_in_main
63f52ef [Davies Liu] fix pylint check
655b8a9 [Davies Liu] Merge branch 'master' of github.com:apache/spark into class_in_main
316a394 [Davies Liu] support Python UDT with UTF
0bcb3ef [Davies Liu] fix bug in mllib
de986d6 [Davies Liu] fix test
83d65ac [Davies Liu] fix bug in StructType
55bb86e [Davies Liu] support Python UDT in __main__ (without Scala one)

`names` is not defined in this context, I think you meant `self.names`.

davies

Author: Alex Angelini <alex.louis.angelini@gmail.com>

Closes #7766 from angelini/fix_struct_type_names and squashes the following commits:

01543a1 [Alex Angelini] Fix reference to self.names in StructType

Author: JD <jd@csh.rit.edu>
Author: Joseph Batchik <josephbatchik@gmail.com>

Closes #7606 from JDrit/expr and squashes the following commits:

ad7f607 [Joseph Batchik] fixing python linter error
9d6daea [Joseph Batchik] removed order by per @rxin's comment
707d5c6 [Joseph Batchik] Added expr to fuctions.py
79df83c [JD] added example to the docs
b89eec8 [JD] moved function up as per @rxin's comment
4960909 [JD] updated per @JoshRosen's comment
2cb329c [JD] updated per @rxin's comment
9a9ad0c [JD] removing unused import
6dc26d0 [JD] removed split
7f2222c [JD] Adding expr function as per SPARK-8668

Romove Decimal.Unlimited (change to support precision up to 38, to match with Hive and other databases).

In order to keep backward source compatibility, Decimal.Unlimited is still there, but change to Decimal(38, 18).

If no precision and scale is provide, it's Decimal(10, 0) as before.

Author: Davies Liu <davies@databricks.com>

Closes #7605 from davies/decimal_unlimited and squashes the following commits:

aa3f115 [Davies Liu] fix tests and style
fb0d20d [Davies Liu] address comments
bfaae35 [Davies Liu] fix style
df93657 [Davies Liu] address comments and clean up
06727fd [Davies Liu] Merge branch 'master' of github.com:apache/spark into decimal_unlimited
4c28969 [Davies Liu] fix tests
8d783cc [Davies Liu] fix tests
788631c [Davies Liu] fix double with decimal in Union/except
1779bde [Davies Liu] fix scala style
c9c7c78 [Davies Liu] remove Decimal.Unlimited

We forgot to update doc. brkyvz

Author: Xiangrui Meng <meng@databricks.com>

Closes #7608 from mengxr/SPARK-9243 and squashes the following commits:

0ea3236 [Xiangrui Meng] null -> zero in crosstab doc

Pull Request for: https://issues.apache.org/jira/browse/SPARK-8230

Primary issue resolved is to implement array/map size for Spark SQL. Code is ready for review by a committer. Chen Hao is on the JIRA ticket, but I don't know his username on github, rxin is also on JIRA ticket.

Things to review:
1. Where to put added functions namespace wise, they seem to be part of a few operations on collections which includes `sort_array` and `array_contains`. Hence the name given `collectionOperations.scala` and `_collection_functions` in python.
2. In Python code, should it be in a `1.5.0` function array or in a collections array?
3. Are there any missing methods on the `Size` case class? Looks like many of these functions have generated Java code, is that also needed in this case?
4. Something else?

Author: Pedro Rodriguez <ski.rodriguez@gmail.com>
Author: Pedro Rodriguez <prodriguez@trulia.com>

Closes #7462 from EntilZha/SPARK-8230 and squashes the following commits:

9a442ae [Pedro Rodriguez] fixed functions and sorted __all__
9aea3bb [Pedro Rodriguez] removed imports from python docs
15d4bf1 [Pedro Rodriguez] Added null test case and changed to nullSafeCodeGen
d88247c [Pedro Rodriguez] removed python code
bd5f0e4 [Pedro Rodriguez] removed duplicate function from rebase/merge
59931b4 [Pedro Rodriguez] fixed compile bug instroduced when merging
c187175 [Pedro Rodriguez] updated code to add size to __all__ directly and removed redundent pretty print
130839f [Pedro Rodriguez] fixed failing test
aa9bade [Pedro Rodriguez] fix style
e093473 [Pedro Rodriguez] updated python code with docs, switched classes/traits implemented, added (failing) expression tests
0449377 [Pedro Rodriguez] refactored code to use better abstract classes/traits and implementations
9a1a2ff [Pedro Rodriguez] added unit tests for map size
2bfbcb6 [Pedro Rodriguez] added unit test for size
20df2b4 [Pedro Rodriguez] Finished working version of size function and added it to python
b503e75 [Pedro Rodriguez] First attempt at implementing size for maps and arrays
99a6a5c [Pedro Rodriguez] fixed failing test
cac75ac [Pedro Rodriguez] fix style
933d843 [Pedro Rodriguez] updated python code with docs, switched classes/traits implemented, added (failing) expression tests
42bb7d4 [Pedro Rodriguez] refactored code to use better abstract classes/traits and implementations
f9c3b8a [Pedro Rodriguez] added unit tests for map size
2515d9f [Pedro Rodriguez] added documentation
0e60541 [Pedro Rodriguez] added unit test for size
acf9853 [Pedro Rodriguez] Finished working version of size function and added it to python
84a5d38 [Pedro Rodriguez] First attempt at implementing size for maps and arrays

Add expressions `regex_extract` & `regex_replace`

Author: Cheng Hao <hao.cheng@intel.com>

Closes #7468 from chenghao-intel/regexp and squashes the following commits:

e5ea476 [Cheng Hao] minor update for documentation
ef96fd6 [Cheng Hao] update the code gen
72cf28f [Cheng Hao] Add more log for compilation error
4e11381 [Cheng Hao] Add regexp_replace / regexp_extract support

This PR adds DataFrame reader/writer shortcut methods for ORC in both Scala and Python.

Author: Cheng Lian <lian@databricks.com>

Closes #7444 from liancheng/spark-9100 and squashes the following commits:

284d043 [Cheng Lian] Fixes PySpark test cases and addresses PR comments
e0b09fb [Cheng Lian] Adds DataFrame reader/writer shortcut methods for ORC

This PR also remove the duplicated code between registerFunction and UserDefinedFunction.

cc JoshRosen

Author: Davies Liu <davies@databricks.com>

Closes #7450 from davies/fix_return_type and squashes the following commits:

e80bf9f [Davies Liu] remove debugging code
f94b1f6 [Davies Liu] fix mima
8f9c58b [Davies Liu] convert returned object from UDF into internal type

JIRA: https://issues.apache.org/jira/browse/SPARK-9101

Author: Mateusz Buśkiewicz <mateusz.buskiewicz@getbase.com>

Closes #7499 from sixers/spark-9101 and squashes the following commits:

dd75aa6 [Mateusz Buśkiewicz] [SPARK-9101] [PySpark] Test for selecting null literal
97e3f2f [Mateusz Buśkiewicz] [SPARK-9101] [PySpark] Add missing NullType to _atomic_types in pyspark.sql.types

This pull request fixes some of the problems in #6981.

- Added date functions to `__all__` so they get exposed
- Rename day_of_month -> dayofmonth
- Rename day_in_year -> dayofyear
- Rename week_of_year -> weekofyear
- Removed "day" from Scala/Python API since it is ambiguous. Only leaving the alias in SQL.

Author: Reynold Xin <rxin@databricks.com>

This patch had conflicts when merged, resolved by
Committer: Reynold Xin <rxin@databricks.com>

Closes #7506 from rxin/datetime and squashes the following commits:

0cb24d9 [Reynold Xin] Export all functions in Python.
e44a4a0 [Reynold Xin] Removed day function from Scala and Python.
9c08fdc [Reynold Xin] [SQL] Make date/time functions more consistent with other database systems.

JIRA: https://issues.apache.org/jira/browse/SPARK-9166

Simply capture and hide `IllegalArgumentException` in Python API.

Author: Liang-Chi Hsieh <viirya@appier.com>

Closes #7497 from viirya/hide_illegalargument and squashes the following commits:

8324dce [Liang-Chi Hsieh] Fix python style.
9ace67d [Liang-Chi Hsieh] Also check exception message.
8b2ce5c [Liang-Chi Hsieh] Merge remote-tracking branch 'upstream/master' into hide_illegalargument
7be016a [Liang-Chi Hsieh] Capture and hide IllegalArgumentException in Python.

[SPARK-8199][SPARK-8184][SPARK-8183][SPARK-8182][SPARK-8181][SPARK-8180][SPARK-8179][SPARK-8177][SPARK-8178][SPARK-9115][SQL] date functions

Jira:
https://issues.apache.org/jira/browse/SPARK-8199
https://issues.apache.org/jira/browse/SPARK-8184
https://issues.apache.org/jira/browse/SPARK-8183
https://issues.apache.org/jira/browse/SPARK-8182
https://issues.apache.org/jira/browse/SPARK-8181
https://issues.apache.org/jira/browse/SPARK-8180
https://issues.apache.org/jira/browse/SPARK-8179
https://issues.apache.org/jira/browse/SPARK-8177
https://issues.apache.org/jira/browse/SPARK-8179
https://issues.apache.org/jira/browse/SPARK-9115

Regarding `day`and `dayofmonth` are both necessary?

~~I am going to add `Quarter` to this PR as well.~~ Done.

~~As soon as the Scala coding is reviewed and discussed, I'll add the python api.~~ Done

Author: Tarek Auel <tarek.auel@googlemail.com>
Author: Tarek Auel <tarek.auel@gmail.com>

Closes #6981 from tarekauel/SPARK-8199 and squashes the following commits:

f7b4c8c [Tarek Auel] [SPARK-8199] fixed bug in tests
bb567b6 [Tarek Auel] [SPARK-8199] fixed test
3e095ba [Tarek Auel] [SPARK-8199] style and timezone fix
256c357 [Tarek Auel] [SPARK-8199] code cleanup
5983dcc [Tarek Auel] [SPARK-8199] whitespace fix
6e0c78f [Tarek Auel] [SPARK-8199] removed setTimeZone in tests, according to cloud-fans comment in #7488
4afc09c [Tarek Auel] [SPARK-8199] concise leap year handling
ea6c110 [Tarek Auel] [SPARK-8199] fix after merging master
70238e0 [Tarek Auel] Merge branch 'master' into SPARK-8199
3c6ae2e [Tarek Auel] [SPARK-8199] removed binary search
fb98ba0 [Tarek Auel] [SPARK-8199] python docstring fix
cdfae27 [Tarek Auel] [SPARK-8199] cleanup & python docstring fix
746b80a [Tarek Auel] [SPARK-8199] build fix
0ad6db8 [Tarek Auel] [SPARK-8199] minor fix
523542d [Tarek Auel] [SPARK-8199] address comments
2259299 [Tarek Auel] [SPARK-8199] day_of_month alias
d01b977 [Tarek Auel] [SPARK-8199] python underscore
56c4a92 [Tarek Auel] [SPARK-8199] update python docu
e223bc0 [Tarek Auel] [SPARK-8199] refactoring
d6aa14e [Tarek Auel] [SPARK-8199] fixed Hive compatibility
b382267 [Tarek Auel] [SPARK-8199] fixed bug in day calculation; removed set TimeZone in HiveCompatibilitySuite for test purposes; removed Hive tests for second and minute, because we can cast '2015-03-18' to a timestamp and extract a minute/second from it
1b2e540 [Tarek Auel] [SPARK-8119] style fix
0852655 [Tarek Auel] [SPARK-8119] changed from ExpectsInputTypes to implicit casts
ec87c69 [Tarek Auel] [SPARK-8119] bug fixing and refactoring
1358cdc [Tarek Auel] Merge remote-tracking branch 'origin/master' into SPARK-8199
740af0e [Tarek Auel] implement date function using a calculation based on days
4fb66da [Tarek Auel] WIP: date functions on calculation only
1a436c9 [Tarek Auel] wip
f775f39 [Tarek Auel] fixed return type
ad17e96 [Tarek Auel] improved implementation
c42b444 [Tarek Auel] Removed merge conflict file
ccb723c [Tarek Auel] [SPARK-8199] style and fixed merge issues
10e4ad1 [Tarek Auel] Merge branch 'master' into date-functions-fast
7d9f0eb [Tarek Auel] [SPARK-8199] git renaming issue
f3e7a9f [Tarek Auel] [SPARK-8199] revert change in DataFrameFunctionsSuite
6f5d95c [Tarek Auel] [SPARK-8199] fixed year interval
d9f8ac3 [Tarek Auel] [SPARK-8199] implement fast track
7bc9d93 [Tarek Auel] Merge branch 'master' into SPARK-8199
5a105d9 [Tarek Auel] [SPARK-8199] rebase after #6985 got merged
eb6760d [Tarek Auel] Merge branch 'master' into SPARK-8199
f120415 [Tarek Auel] improved runtime
a8edebd [Tarek Auel] use Calendar instead of SimpleDateFormat
5fe74e1 [Tarek Auel] fixed python style
3bfac90 [Tarek Auel] fixed style
356df78 [Tarek Auel] rely on cast mechanism of Spark. Simplified implementation
02efc5d [Tarek Auel] removed doubled code
a5ea120 [Tarek Auel] added python api; changed test to be more meaningful
b680db6 [Tarek Auel] added codegeneration to all functions
c739788 [Tarek Auel] added support for quarter SPARK-8178
849fb41 [Tarek Auel] fixed stupid test
638596f [Tarek Auel] improved codegen
4d8049b [Tarek Auel] fixed tests and added type check
5ebb235 [Tarek Auel] resolved naming conflict
d0e2f99 [Tarek Auel] date functions

- `BinaryType` for `Length`
- `FormatNumber`

Author: Cheng Hao <hao.cheng@intel.com>

Closes #7034 from chenghao-intel/expression and squashes the following commits:

e534b87 [Cheng Hao] python api style issue
601bbf5 [Cheng Hao] add python API support
3ebe288 [Cheng Hao] update as feedback
52274f7 [Cheng Hao] add support for udf_format_number and length for binary

It may loss a microsecond if using timestamp as float, should be `int` instead.

Author: Davies Liu <davies@databricks.com>

Closes #7363 from davies/fix_microsecond and squashes the following commits:

36f6007 [Davies Liu] fix microsecond loss in Python 3

It may loss precision in microseconds when using float for it.

Author: Davies Liu <davies@databricks.com>

Closes #7344 from davies/fix_date_test and squashes the following commits:

249ec61 [Davies Liu] fix flaky test