[Python-Dev] Re: [Python-checkins] python/nondist/sandbox/spambayes GBayes.py,1.7,1.8

[Tim Peters]

[Tim]
> ...
>     P(S|X) = (100+100)/200 = 1/2
> and
>     P(S|Y) = (500+500)/500 = 1/2
>
> too by the same reasoning.  P(not-S|X) and P(not-S|Y) are also 1/2 each.
>
> So far, there's nothing a reasonable person can argue with.

And note that only an unreasonable person would argue that (100+100)/200 =
1, so don't even think about it <wink>.  Of course those should have been

     P(S|X) = 100/(100+100) = 1/2
 and
     P(S|Y) = 500/(500+500) = 1/2

There are probably other glitches like that.  Work out the example
yourself -- it's much easier to figure it out than to transcribe all the
tedious numbers into a msg.