Hi Nikos, On Tue, Oct 30, 2012 at 7:35 AM, Nikos Alexandris <[email protected]> wrote: ... > I wonder why the term ISODATA [2] is not to be traced anywhere in the GRASS > manuals, nor in the GRASS book (3rd ed.). Can someone confirm that i.cluster > is an(other) implementation of the ISODATA clustering algorithm?
I search in my inbox and found some earlier discussion with the Subject: "Re: [GRASS-user] Re: algorithm used in i.cluster", see below. cheers Markus PS: Still we need a text snippet to improve the manual... On Thu, Apr 22, 2010 at 5:21 PM, Georg Kaspar <georg - muenster.de> wrote: > Georg Kaspar schrieb: > >> the steps described in >> http://download.osgeo.org/grass/grass6_progman/c__exec_8c_source.html >> >> seem to fit the migrating means algorithm described in richards and jia >> (2006) and based on the isodata algorithm in ball and hall (1965): > > which is in principle the same as k-means. > I wrote a mail to Michael Shapiro, who wrote the code back in the 90's and > received this answer: > >> Georg, >> >> It has been a very long time since I wrote that code so my memory may be >> suspect, but I think that is correct. On Thu, Apr 22, 2010 at 5:35 PM, Georg Kaspar <[email protected]> wrote: > Sorry for flooding the list, but i found an interesting note in Schowengerdt > (2007), p. 400: > > "The ISODATA algorithm (Ball and Hall, 1967) is a common modification of the > K-means algorithm and includes merging of clusters if their separation is > below a threshold, and splitting of a single cluster into two clusters if it > becomes too large" > > The algorithm implemented in the i.cluster module involves merging of > classes (I_cluster_merge) though no splitting function seems to be > implemented. > Since Michael Shapiro stated that he might have used the K-means algorithm, > I think we can be pretty shure that it is a modified version similar to the > isodata algorithm, which is described as migrating means in Richards (2006). > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
