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

Switch to Threaded View
Hive, mail # user - Combine multiple row values based upon a condition.


Copy link to this message
-
Re: Combine multiple row values based upon a condition.
Edward Capriolo 2013-02-03, 19:36
You may want to look at sort by, distribute by, and cluster by. This
syntax controls which Reducers the data end up on and how it is sorted
on each reducer.

On Sun, Feb 3, 2013 at 2:27 PM, Martijn van Leeuwen
<[EMAIL PROTECTED]> wrote:
> yes there is. Each document has a UUID as its identifier. The actual output
> of my map reduce job that produces the list of person names looks like this
>
> docId        Name Type length offset
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Lea     PERSON     3     10858
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Lea     PERSON     3     11063
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Ken     PERSON     3     11186
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Marottoli     PERSON     9
> 11234
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Berkowitz     PERSON     9
> 17073
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Lea     PERSON     3     17095
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Stephanie     PERSON     9
> 17330
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Putt     PERSON     4     17340
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Stephanie     PERSON     9
> 17347
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Stephanie     PERSON     9
> 17480
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Putt     PERSON     4     17490
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Berkowitz     PERSON     9
> 19498
> f83c6ca3-9585-4c66-b9b0-f4c3bd57ccf4     Stephanie     PERSON     9
> 19530
>
> Use the following code to produce a table inside Hive.
>
> DROP TABLE IF EXISTS entities_extract;
>
>     CREATE TABLE entities_extract (doc_id STRING, name STRING, type STRING,
> len INT, offset BIGINT)
>     ROW FORMAT DELIMITED FIELDS TERMINATED BY '\t'
>     LINES TERMINATED BY '\n'
>     STORED AS TEXTFILE
>     LOCATION '/research/45924/hive/entities_extract';
>
> LOAD DATA LOCAL INPATH
> '/home/researcher/hadoop-runnables/files/entitie_extract_by_doc.txt'
> OVERWRITE INTO TABLE entities_extract;
>
>
>
> On Feb 3, 2013, at 8:07 PM, John Omernik <[EMAIL PROTECTED]> wrote:
>
> Is there some think akin to a document I'd so we can assure all rows
> belonging to the same document can be sent to one mapper?
>
> On Feb 3, 2013 1:00 PM, "Martijn van Leeuwen" <[EMAIL PROTECTED]> wrote:
>>
>> Hi John,
>>
>> Here is some background about my data and what I want as output.
>>
>> I have a 215K documents containing text. From those text files I extract
>> names of persons, organisations and locations by using the Stanford NER
>> library. (see http://nlp.stanford.edu/software/CRF-NER.shtml)
>>
>> Looking at the following line:
>>
>> Jan Janssen was on this way to Klaas to sell vehicle Jan Janssen stole
>> from his father.
>>
>> when the classifier is done annotating the line looks like this:
>>
>> <PERSON>Jan<PERSON><OFFSET>0<OFFSET>
>> <PERSON>Janssen<PERSON><OFFSET>5<OFFSET> was on this way to
>> <PERSON>Klaas<PERSON><OFFSET>26<OFFSET> to sell the vehicle
>> <PERSON>Jan<PERSON><OFFSET>48<OFFSET>
>> <PERSON>Janssen<PERSON><OFFSET>50<OFFSET> stole from his father.
>>
>> When looping through this annotated line you can save the persons and its
>> offsets, please note that offset is a LONG value, inside a Map for example:
>>
>> MAP<STRING, LONG> entities
>>
>> Jan, 0
>> Janssen, 5
>> Klaas, 26
>> Jan, 48
>> Janssen, 50
>>
>> Jan Janssen in the line is actually the one person and not two. Jan occurs
>> at offset 0, to determine if Janssen belongs to Jan I could subtract the
>> length of Jan (3) + 1 (whitespace) from Janssen's offset (5) and if outcome
>> isn't greater then 1 then combine the two person into one person.
>>
>> (offset Jansen) - (offset Jan + whitespace) not greater then 1
>>
>> If this is true then combine the two person and save this inside a new
>> MAP<STRING, LONG[]> like
>> Jan Janssen, [ 0 ].
>>
>> The next time we come across Jan Janssen inside the text then just save
>> the offset. Which produces the following MAP<STRING, LONG[]>
>>
>> Jan Janssen, [0, 48]
>>
>> I hope this clarifies my question.
>> If things are still unclear please don't hesitate to ask me to clarify my