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Bug reporting
If you have any problems with this software, please e-mail me at:
peteymills@hotmail.com
If you can describe the problem clearly and succinctly, I can probably have a patch ready for you within the next day or two.
2009-09-04 16:59:28 UTC by peteysoft
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We now have clustering!
A simple clustering analysis program has been added to the mix. My initial goal was to use a threshold density and find all the iso-surfaces for that density, possibly using an algorithm similar to that for finding class borders. This should be simpler and faster than a hierarchical clustering, although less general since the analysis will need to be repeated every time we try a different threshold. I didn't want to just write a hierarchichal clustering algorithm since it doesn't really "fit" with the rest of the library.
In the end, I came up with a very simple method of using the k-nearest neighbours to cluster points above the threshold density together. A similar method could be used with AGF using both a threshold density and a threshold distance; the distance could be calculated from the density.
2009-09-01 10:23:35 UTC by peteysoft
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New release for libagf--0.92
The new release includes many bug fixes--they were legion--but also some improved functionality.
Direct classification routines will now return the joint probabilities in addition to conditional probabilities. Since you can use either for classification, the joint probabilities provide more information.
It is now possible to search for a class border at some point other than R=0. This is useful if the classes differ greatly in size or if the relative number of samples do not reflect the actual class sizes.
You can use other metrics than Cartesian. There are some issues with that.
We now have n-fold cross validation!--for the classification routines, at least. It still needs to be added for the interpolation/non-linear regression routines.
We also have clustering. This will be detailed in a subsequent post.
2009-09-01 10:12:51 UTC by peteysoft
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Planned improvements
Through my own use of the software, at least two short-comings have become apparent:
1. when the classes are broadly separated, class_borders fails to converge. The fix is likely fairly simple, but will involve a minor "hack."
2. to calculate joint probabilities, you need to make two calls: one to a classification routine and then another to a pdf calculation routine. This is wasteful as it could be done in a single step.
2009-06-25 14:28:14 UTC by peteysoft
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Bug reporting and attribution
The libagf project has been sitting on sourceforge for over two years now and I've witnessed a steady stream of downloads throughout that time. In spite of this I have yet see a single e-mail either asking for help, requesting bug fixes, thanking me or simply informing me of its use.
If you use this package in your work, please help spread the word by referencing either the website, the included documentation or the following paper:
Peter Mills 2009, "Isoline retrieval: An optimal method for validation of advected contours." Computers & Geosciences, in press (available online).
2009-06-25 13:19:57 UTC by peteysoft
