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From "Cheolsoo Park (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (PIG-2905) Improve documentation around REPLACE
Date Wed, 05 Sep 2012 02:30:08 GMT

     [ https://issues.apache.org/jira/browse/PIG-2905?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Cheolsoo Park updated PIG-2905:
-------------------------------

    Attachment: PIG-2905.patch

I added the following text to the REPLACE doc:
{quote}
Note that the REPLACE function is internally implemented using [java.string.replaceAll(String
regex, String replacement)|http://docs.oracle.com/javase/6/docs/api/java/lang/String.html#replaceAll(java.lang.String,
java.lang.String)] where 'regExp' and 'newChar' are passed as the 1st and 2nd argument respectively.
If you want to replace [special characters|http://docs.oracle.com/javase/6/docs/api/java/util/regex/Pattern.html#bs]
such as '[' in the string literal, it is necessary to escape them in 'regExp' by prefixing
them with double backslashes.
{quote}

Thanks!
                
> Improve documentation around REPLACE
> ------------------------------------
>
>                 Key: PIG-2905
>                 URL: https://issues.apache.org/jira/browse/PIG-2905
>             Project: Pig
>          Issue Type: Sub-task
>          Components: documentation
>            Reporter: Bill Graham
>            Assignee: Cheolsoo Park
>         Attachments: PIG-2905.patch
>
>
> Document how REPLACE uses a Java regex and link out to JDK docs describing reserved characters
and escaping. From recent confusion on the users list:
> {noformat}
> > String source = "[02/Aug/2012:05:01:17";
> > > String target ="[";
> > > String replaceWith = "";
> > > return source.replaceAll(source, target, replaceWith);
> > Note that Java String.replaceAll() takes a regular expression for the 2nd
> > parameter (i.e. target), and "[" is a special character. To use it as is,
> > you have to escape it, so in your Pig script, you should do:
> > REPLACE(date,'\\[','')
> {noformat} 

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