GitHub user kevinyu98 opened a pull request:
https://github.com/apache/spark/pull/19329
[SPARK-22110][SQL][Documentation] Add usage and improve documentation with
arguments and examples for trim function
## What changes were proposed in this pull request?
This PR proposes to enhance the documentation for `trim` functions in the
function description session.
- Add more `usage`, `arguments` and `examples` for the trim function
- Adjust space in the `usage` session
After the changes, the trim function documentation will look like this:
- `trim`
```trim(str) - Removes the leading and trailing space characters from str.
trim(BOTH trimStr FROM str) - Remove the leading and trailing trimStr
characters from str
trim(LEADING trimStr FROM str) - Remove the leading trimStr characters from
str
trim(TRAILING trimStr FROM str) - Remove the trailing trimStr characters
from str
Arguments:
str - a string expression
trimStr - the trim string characters to trim, the default value is a single
space
BOTH, FROM - these are keywords to specify trimming string characters from
both ends of the string
LEADING, FROM - these are keywords to specify trimming string characters
from the left end of the string
TRAILING, FROM - these are keywords to specify trimming string characters
from the right end of the string
Examples:
> SELECT trim(' SparkSQL ');
SparkSQL
> SELECT trim('SL', 'SSparkSQLS');
parkSQ
> SELECT trim(BOTH 'SL' FROM 'SSparkSQLS');
parkSQ
> SELECT trim(LEADING 'SL' FROM 'SSparkSQLS');
parkSQLS
> SELECT trim(TRAILING 'SL' FROM 'SSparkSQLS');
SSparkSQ
```
- `ltrim`
```ltrim
ltrim(str) - Removes the leading space characters from str.
ltrim(trimStr, str) - Removes the leading string contains the characters
from the trim string
Arguments:
str - a string expression
trimStr - the trim string characters to trim, the default value is a single
space
Examples:
> SELECT ltrim(' SparkSQL ');
SparkSQL
> SELECT ltrim('Sp', 'SSparkSQLS');
arkSQLS
```
- `rtrim`
```rtrim
rtrim(str) - Removes the trailing space characters from str.
rtrim(trimStr, str) - Removes the trailing string which contains the
characters from the trim string from the str
Arguments:
str - a string expression
trimStr - the trim string characters to trim, the default value is a single
space
Examples:
> SELECT rtrim(' SparkSQL ');
SparkSQL
> SELECT rtrim('LQSa', 'SSparkSQLS');
SSpark
```
This is the trim characters function jira: [trim
function](https://issues.apache.org/jira/browse/SPARK-14878)
## How was this patch tested?
Manually tested
```
spark-sql> describe function extended trim;
17/09/22 17:03:04 INFO CodeGenerator: Code generated in 153.026533 ms
Function: trim
Class: org.apache.spark.sql.catalyst.expressions.StringTrim
Usage:
trim(str) - Removes the leading and trailing space characters from
`str`.
trim(BOTH trimStr FROM str) - Remove the leading and trailing `trimStr`
characters from `str`
trim(LEADING trimStr FROM str) - Remove the leading `trimStr`
characters from `str`
trim(TRAILING trimStr FROM str) - Remove the trailing `trimStr`
characters from `str`
Extended Usage:
Arguments:
* str - a string expression
* trimStr - the trim string characters to trim, the default value is
a single space
* BOTH, FROM - these are keywords to specify trimming string
characters from both ends of
the string
* LEADING, FROM - these are keywords to specify trimming string
characters from the left
end of the string
* TRAILING, FROM - these are keywords to specify trimming string
characters from the right
end of the string
Examples:
> SELECT trim(' SparkSQL ');
SparkSQL
> SELECT trim('SL', 'SSparkSQLS');
parkSQ
> SELECT trim(BOTH 'SL' FROM 'SSparkSQLS');
parkSQ
> SELECT trim(LEADING 'SL' FROM 'SSparkSQLS');
parkSQLS
> SELECT trim(TRAILING 'SL' FROM 'SSparkSQLS');
SSparkSQ
```
```
spark-sql> describe function extended ltrim;
Function: ltrim
Class: org.apache.spark.sql.catalyst.expressions.StringTrimLeft
Usage:
ltrim(str) - Removes the leading space characters from `str`.
ltrim(trimStr, str) - Removes the leading string contains the
characters from the trim string
Extended Usage:
Arguments:
* str - a string expression
* trimStr - the trim string characters to trim, the default value is
a single space
Examples:
> SELECT ltrim(' SparkSQL ');
SparkSQL
> SELECT ltrim('Sp', 'SSparkSQLS');
arkSQLS
```
```
spark-sql> describe function extended rtrim;
Function: rtrim
Class: org.apache.spark.sql.catalyst.expressions.StringTrimRight
Usage:
rtrim(str) - Removes the trailing space characters from `str`.
rtrim(trimStr, str) - Removes the trailing string which contains the
characters from the trim string from the `str`
Extended Usage:
Arguments:
* str - a string expression
* trimStr - the trim string characters to trim, the default value is
a single space
Examples:
> SELECT rtrim(' SparkSQL ');
SparkSQL
> SELECT rtrim('LQSa', 'SSparkSQLS');
SSpark
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/kevinyu98/spark spark-14878-5
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/19329.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #19329
----
commit 7ecbe4c28087564f1ba0adaa62a12cd28be351c0
Author: Kevin Yu <q...@us.ibm.com>
Date: 2017-09-20T21:35:57Z
adding examples for stringTrim string function
commit 4f77d95cbd2492db0d398612dd28a0a89ea849fd
Author: Kevin Yu <q...@us.ibm.com>
Date: 2017-09-21T06:00:46Z
adjust comments
commit 0f3307dfc3dd21b3d643d3d58e9202743f958b23
Author: Kevin Yu <q...@us.ibm.com>
Date: 2017-09-22T22:46:02Z
rebase
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