[Rd] fuzzy c-means algorithm in e1071

From: Tim Smyth <tjsm_at_pml.ac.uk>
Date: Fri, 15 Jul 2011 01:11:22 -0700 (PDT)

I was wondering if it was possible to add an extra option to the cmeans function please? In a recent paper by Moore et al.,(2009) they state:

"The fuzzy membership function is: 1 - F(Z2), where Z2 is a squared Mahalanobis distance and F is a cumulative chi-square distribution. The Mahalanobis distance is the multivariate equivalent of the standardised random variable Z = (X - M)/S, which is the distance of the univariate random variable X from its mean M normalised by the standard deviation S. In other words, the Mahalanobis distance is a weighted form of the Euclidean, and is preferable because it incorporates the shape of the the distribution of points around the cluster centre (i.e., the geometric shape of the point cloud expressed in terms of variance). The fuzzy membership ranges from 0 to 1 ..."

so as well as having a dist = "euclidean" option, would it be possible to have a dist = "mahalanobis" option please? I realise that this is quite an ask - you could even point me in the right direction of where to start editing code and getting it compiled on my own machine.

Tim Smyth

ref: T.S. Moore et al. Remote Sensing of Environment 113 (2009) 2424-2430

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