Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
Pig >> mail # user >> Replace null with string


Copy link to this message
-
Re: Replace null with string
fixed = FOREACH my_relation GENERATE (my_field IS NOT NULL ? my_field
: 'other') as my_field, *;

Russell Jurney
twitter.com/rjurney
[EMAIL PROTECTED]
datasyndrome.com

On Jun 8, 2012, at 3:01 PM, Dragan Nedeljkovic <[EMAIL PROTECTED]> wrote:

> You can use an UDF like the one bellow to deal with  the NULLs.
>
> register 'mypiggybank.jar';
> define Nvl piggybank.Nvl();
>
> input_lines = LOAD 'test_Nvl.in' AS (line:chararray);
> describe input_lines;
> dump input_lines;
>
> new_list = FOREACH input_lines GENERATE Nvl(line, 'n/a');
> describe new_list;
> dump new_list;
>
> -- eof
>
> package piggybank;
>
> import java.io.IOException;
>
> import org.apache.pig.EvalFunc;
> import org.apache.pig.data.Tuple;
>
> public class Nvl
>    extends EvalFunc<String>
> {
>    public String exec(Tuple inputA)
>       throws IOException
>    {
>       try
>       {
>          String inputVal = (String)inputA.get(0);
>          String defaultVal = (String)inputA.get(1);
>
>          if(inputVal == null || inputVal.length() == 0)
>          {
>             return defaultVal;
>          }
>
>          return inputVal;
>       }
>       catch(Exception e)
>       {
>          // Throwing an exception will cause the task to fail.
>          throw new IOException("Something bad happened!", e);
>       }
>    }
> }
> // eof
>
>
>
>
>> ________________________________
>> From: Mario Lassnig <[EMAIL PROTECTED]>
>> To: [EMAIL PROTECTED]
>> Sent: Thursday, June 7, 2012 7:37:36 AM
>> Subject: Replace null with string
>>
>> Hello,
>>
>> I'm having a lot of null entries in my data. Due to later processing it would be very helpful if I could set a default value for null to be the string "other". I couldn't find a way to do this (version 0.8.1-cdh3u4)
>>
>> Also, I have some variables in my GENERATE statements that can potentially return null, and I would need something similar to the SQL DECODE function to get the "other" string instead of null.
>>
>> Example:
>>
>> tmp = FOREACH dump GENERATE site, REGEX_EXTRACT(name, '^(?:([^.]+)\\.?){1}', 1) AS project, ((ami MATCHES '.*datatype.*') ? REGEX_EXTRACT(name, '^(?:([^.]+)\\.?){5}', 1) : 'other') AS datatype, ami, duid, nbfiles, length, rnbfiles, rlength, name;
>>
>> Here: 'site' and 'datatype' could return an empty string (which is valid) and is interpreted as null, but should be "other" instead.
>>
>> Thanks a lot,
>> Mario
>>
>>