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Sparse Array Format for Maxent

2006-02-15
2013-04-11
  • goodspeed99

    goodspeed99 - 2006-02-15

    Hi is there some file format for entering sparse
    feature arrays?  I have training data with 13K features most of them are zeros. 

    Craig

     
    • Thomas Morton

      Thomas Morton - 2006-02-16

      Hi,
         The default formats (such as the ones shown in the sample data) are designed to be sparse with zero valued features not being explicitly represented.  Any feature which is listed is considered to occur once and features which occur more than once in an event are simply listed as many times as they occur.   For instance if I'm build a "how good was my day classifier" and I think the number of meetings I have is a good indicator, then one day might look like:

      so-so: traffic meeting meeting coding no_traffic ice_cream

      indicating that I had two meetings.  Notice there is no representation of the "snowboarding" feature (which highly correlated with good days) since it didn't occur on this day.

      Thus, if you have event data with 0 valued features, simply remove those features when you construct your event space.

      Take a look at the samples since they go through this in much more detail.  Hope this helps...Tom

       

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