problems with 'select by random' operator [SOLVED]

[sfmorais]

Hi!

I have the same problem than
http://rapid-i.com/rapidforum/index.php/topic,3708.msg13825.html#msg13825
but I didn´t understand the solution.

I have a example set with some atributes. I want select one randomly atribute (for example with 'select by random' operator), but each time that I run the process the selected attribute is always the same.

How can I workaround it ?  (if possible with a example)

Many thanks for the help

Best Regards,
Sérgio Morais

[Marco Boeck]

Hi,

that is because the local random seed is fixed by default to allow reproduction of results. You can change that by selecting the process, and change the "random seed" parameter to -1.
That way, the random function will use the current system time, and you will get a more random selection of attributes.

Regards,
Marco

[sfmorais]

Hi,

I tried solve the problem in two different ways:

1) In my process, in 'select by random' operator I tried changed 'local random seed' to -1 but the value is converted to 1 automatically

2) In Rapid Miner 'Tools -> Preferences' I changed 'rapidminer.general.randomseed' option to '-1' and apply, and the problem is the same.


I still with same problem (the selected attribute is always the same)
(if necessary I send the xml of my problem)

Many Thanks in advance

Regards

[Marius]

Hi,

Marco was referring to the random seed of the Process, not of the operator. Just click an empty space in the process pane to see the properties of the process itself. Set the random seed to -1. Additionally, disable "use local random seed" for the Select by Random operator.

Best,
Marius

[sfmorais]

Ok! now I understood. It works!   

Thanks