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From "Mendelson, Assaf" <Assaf.Mendel...@rsa.com>
Subject RE: Aggregate UDF (UDAF) in Python
Date Mon, 17 Oct 2016 17:50:41 GMT
A possible (bad) workaround would be to use the collect_list function. This will give you all
the values in an array (list) and you can then create a UDF to do the aggregation yourself.
This would be very slow and cost a lot of memory but it would work if your cluster can handle
it.
This is the only workaround I can think of, otherwise you  will need to write the UDAF in
java/scala and wrap it for python use. If you need an example on how to do so I can provide
one.
Assaf.

From: Tobi Bosede [mailto:ani.tobib@gmail.com]
Sent: Sunday, October 16, 2016 7:49 PM
To: Holden Karau
Cc: user
Subject: Re: Aggregate UDF (UDAF) in Python

OK, I misread the year on the dev list. Can you comment on work arounds? (I.e. question about
if scala/java are the only option.)

On Sun, Oct 16, 2016 at 12:09 PM, Holden Karau <holden@pigscanfly.ca<mailto:holden@pigscanfly.ca>>
wrote:
The comment on the developer list is from earlier this week. I'm not sure why UDAF support
hasn't made the hop to Python - while I work a fair amount on PySpark it's mostly in core
& ML and not a lot with SQL so there could be good reasons I'm just not familiar with.
We can try pinging Davies or Michael on the JIRA to see what their thoughts are.

On Sunday, October 16, 2016, Tobi Bosede <ani.tobib@gmail.com<mailto:ani.tobib@gmail.com>>
wrote:
Thanks for the info Holden.

So it seems both the jira and the comment on the developer list are over a year old. More
surprising, the jira has no assignee. Any particular reason for the lack of activity in this
area?

Is writing scala/java the only work around for this? I hear a lot of people say python is
the gateway language to scala. It is because of issues like this that people use scala for
Spark rather than python or eventually abandon python for scala. It just takes too long for
features to get ported over from scala/java.


On Sun, Oct 16, 2016 at 8:42 AM, Holden Karau <holden@pigscanfly.ca<mailto:holden@pigscanfly.ca>>
wrote:
I don't believe UDAFs are available in PySpark as this came up on the developer list while
I was asking for what features people were missing in PySpark - see http://apache-spark-developers-list.1001551.n3.nabble.com/Python-Spark-Improvements-forked-from-Spark-Improvement-Proposals-td19422.html
. The JIRA for tacking this issue is at https://issues.apache.org/jira/browse/SPARK-10915

On Sat, Oct 15, 2016 at 7:20 PM, Tobi Bosede <ani.tobib@gmail.com<mailto:ani.tobib@gmail.com>>
wrote:
Hello,

I am trying to use a UDF that calculates inter-quartile (IQR) range for pivot() and SQL in
pyspark and got the error that my function wasn't an aggregate function in both scenarios.
Does anyone know if UDAF functionality is available in python? If not, what can I do as a
work around?

Thanks,
Tobi



--
Cell : 425-233-8271<tel:425-233-8271>
Twitter: https://twitter.com/holdenkarau



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Cell : 425-233-8271<tel:425-233-8271>
Twitter: https://twitter.com/holdenkarau


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