[Biojava-l] log-odds ratio

Matthew Pocock matthew_pocock at yahoo.co.uk
Wed Mar 19 17:55:12 EST 2003


The dynamic programing code all use log odds (or log probabilities for 
forwards/backwards training) for exactly this reason. I guess weight 
matricies should do this too. If you're searching with a long weight 
matrix, then you should probably be using a profile HMM though.

Matthew

Ren, Zhen wrote:
> Hi, there,
> 
> The WeightMatrixDemo example at "BioJava In Anger" page (http://bioconf.otago.ac.nz/biojava/weightMatrix.htm?PHPSESSID=0adccafdabe1f2c52b062649c404c50f generates a WeightMatrix from an aligment and uses that matrix to annotate a Sequence with a threshold of 0.1.  This program uses the odds ratio.  I wonder if BioJava has the capacity to use the log-odds ratio (an additive scoring system) to avoid overflow.  So, I guess very slight modification can do the same thing as this program does.  Thanks.
> 
> Zhen
> 
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