Fri Jul 23 19:46:46 CDT 2010
On Fri, Jul 23, 2010 at 6:48 PM, Keith Goodman <email@example.com> wrote:
> On Fri, Jul 23, 2010 at 4:00 PM, Benjamin Root <firstname.lastname@example.org> wrote:
> > The stopping condition uses the change in the distortion, not a
> > distance. The distortion is already a sum of squares. The only place
> > a non-squared distance is used is in _py_vq_1d() which appears to be very
> > old code and it has a raise error at the very first statement.
> That's good news.
> Another place that a non-squared distance is used is the return value:
> >> import numpy as np
> >> from scipy import cluster
> >> v = np.array([1,2,3,4,10],dtype=float)
> >> cluster.vq.kmeans(v, 1)
> (array([ 4.]), 2.3999999999999999)
> >> np.sqrt(np.dot(v-4, v-4) / 5.0)
> 3.1622776601683795 # Nope, not returned
> >> np.absolute(v - 4).mean()
> 2.3999999999999999 # Yep, this one is returned
> Is that a code bug or a doc bug?
Well, see, that's just the thing... the doc says that it returns the
distortion, which is what it does, but obviously, this distortion was a MAE
and not a RMSE. The problem is that I have gone backwards and forwards over
the codes, including the Cython version, and I can't find anyplace where
this is happening.
Does anybody know of any good code tracing tools? I used trace once, but it
wasn't very user-friendly...
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