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Thread: Setting up custom threshold

  1. #1
    Join Date
    Feb 2015
    Posts
    10

    Default Setting up custom threshold

    Hi,
    I have a two vectors csv.
    1 - continuous scores between 0 to 1. (Numerical)
    2 - Yes/No (Nominal).

    I would like WEKA to predict Yes/No according to a threshold I would set for the values in column 1.
    Meaning, if the score in column 1 is higher than the threshold that I will give, than the prediction of WEKA should be 1. else 0.

    The reason is that I want to see its ROC curve and the AUC.

    What classifier should I use and how can I set the threshold?

    Thank you,
    Tamir

  2. #2
    Join Date
    Aug 2006
    Posts
    1,741

    Default

    It doesn't sound like you need a classifier at all as you already have a score to threshold on. However, if you are wanting to use Weka's ROC plotting stuff then you will need to implement a classifier (as the routine works from the predictions generated by a classifier). Using Weka's Groovy or Jython scripting support this should be pretty easy to do. You will need the scriptingClassifiers package (installable from Weka's package manager):

    http://weka.sourceforge.net/packageM...ers/index.html

    The Wiki has some pages on writing scripting-based classifiers:

    http://weka.wikispaces.com/Using+Weka+from+Groovy
    http://weka.wikispaces.com/Using+Weka+from+Jython

    Cheers,
    Mark.

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