Re: UDF Request "AGGLOM()"

2005-12-05 Thread dmb
> Hi Dan,
>
> Dan Bolser wrote:
 Who can I prod about setting up a UDF repo at MySQL. I think 'they'
 should
 do this ;)
>>> Yep it's an existing idea, a very good one, and it's on the todo.
>>> Putting such an infrastructure into place will take some time though.
>>
>> I can imagine it isn't trivial to set up.
>>
>>> Would a special forum for this purpose perhaps be a good intermediate
>>> solution? Routines could be posted there, it's searchable...
>>
>> Forum = list?
>>
>> I think it would be a good start, if only to discuss things like this :)
>
> forums.mysql.com


Thanks. Don't know if it is just me, but I can't find anything to do with
UDF's on that forum. I was actually thinking that you meant an archived
mailing list, but a BBS is OK.




> Regards,
> Arjen.
> --
> Arjen Lentz, Community Relations Manager, MySQL AB
> Program Chair, MySQL Users Conference
>
> MySQL Users Conference 2006 (Santa Clara CA, 24-27 April)
> http://www.mysqluc.com/
>



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Re: UDF Request "AGGLOM()"

2005-12-05 Thread Arjen Lentz

Hi Dan,

Dan Bolser wrote:

Who can I prod about setting up a UDF repo at MySQL. I think 'they' should
do this ;)

Yep it's an existing idea, a very good one, and it's on the todo.
Putting such an infrastructure into place will take some time though.


I can imagine it isn't trivial to set up.


Would a special forum for this purpose perhaps be a good intermediate
solution? Routines could be posted there, it's searchable...


Forum = list?

I think it would be a good start, if only to discuss things like this :)


forums.mysql.com


Regards,
Arjen.
--
Arjen Lentz, Community Relations Manager, MySQL AB
Program Chair, MySQL Users Conference

MySQL Users Conference 2006 (Santa Clara CA, 24-27 April)
http://www.mysqluc.com/

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Re: UDF Request "AGGLOM()"

2005-04-11 Thread Dan Bolser
On Mon, 11 Apr 2005, Arjen Lentz wrote:

>Hi Dan,
>
>On Sat, 2005-04-09 at 02:59, Dan Bolser wrote:
>> Who can I prod about setting up a UDF repo at MySQL. I think 'they' should
>> do this ;)
>
>Yep it's an existing idea, a very good one, and it's on the todo.
>Putting such an infrastructure into place will take some time though.

I can imagine it isn't trivial to set up.

>Would a special forum for this purpose perhaps be a good intermediate
>solution? Routines could be posted there, it's searchable...

Forum = list?

I think it would be a good start, if only to discuss things like this :)

All the best,
Dan.


>
>
>Regards,
>Arjen.
>


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Re: UDF Request "AGGLOM()"

2005-04-10 Thread Arjen Lentz
Hi Dan,

On Sat, 2005-04-09 at 02:59, Dan Bolser wrote:
> Who can I prod about setting up a UDF repo at MySQL. I think 'they' should
> do this ;)

Yep it's an existing idea, a very good one, and it's on the todo.
Putting such an infrastructure into place will take some time though.

Would a special forum for this purpose perhaps be a good intermediate
solution? Routines could be posted there, it's searchable...


Regards,
Arjen.
-- 
Arjen Lentz, Community Relations Manager
MySQL AB, www.mysql.com

MySQL Users Conference (Santa Clara CA, 18-21 April 2005)
Only 8 days until the event!  http://www.mysqluc.com/



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UDF Request "AGGLOM()"

2005-04-08 Thread Dan Bolser

Who can I prod about setting up a UDF repo at MySQL. I think 'they' should
do this ;)

http://lists.mysql.com/community/97

Anyway I am posting this request to 'community' because I still don't know
the appropriate place to post UDF related stuff.

This is anoter (potentially crazy) idea for a UDF that I would find very
usefull in my research...

AGGLOM - Simple agglomerative clustering for MySQL ...

The UDF would work on any NUMBER column, and return the
number of 'clusters' using agglomerative clustering
with a certain threshold as an input.

Agglomerative clustering merges any two numbers that
are within the 'threshold', and replaces those numbers
with the average of the two. The clustering proceedes
smallest 'gap' first, and stops when no two numbers are
within the threshold.

The result would be the number (or perhaps the values) of the
remaining clusters.

Syntax (suggested) 

AGGLOM(THRESH,expr (returning a number))

For example

Table1

C1 C2
A 1
A 2
A 3
A 4
A 5
A 6
A 7
B 10
B 11
B 12
B 56
B 57
B 58
B 99
B 101


SELECT C1, AGGLOM(C2,1) AS C3 FROM Table1 GROUP BY C1;

C1 C3
A 4
B 6


SELECT C1, AGGLOM(C2,2) AS C3 FROM Table1 GROUP BY C1;

C1 C3
A 3
B 3


SELECT C1, AGGLOM(C2,3) AS C3 Table1 GROUP BY C1;

C1 C3
A 2
B 3


SELECT C1, AGGLOM(C2,4) AS C3 Table1 GROUP BY C1;

C1 C3
A 1
B 3


SELECT C1, AGGLOM(C2,50) AS C3 Table1 GROUP BY C1;

C1 C3
A 1
B 1



Remember, merge numbers with the smallest difference
first, and replace each pair with the average of the
two. Recalculate the differences for the new number,
and repeat until no distance is smaller than the threshold.

This is a usefull clustering 'hack' to see if a distribution 
is bi-modal or multi modal for example. It is very quick to
calculate using a hash table, and could be a great
function to add.

Is this idea as crazy as I think it might be?




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