Dear R-help.. I am rather new in R so i would appreciate your help in my problem.. I have 3 types of vegetation (A,B,C),50 measurements per class and 100 variables per measurement. I would like to perform seperability analysis between these classes meaning... a.)create the hypercube from these 100 variables b.)"plot" the 50 measurements for each class and identify the position of the center of each class.. c.)calculate the distances between each class center using Euclidean, Jeffries-Matusita or other measures. I have tried searching all keywords at CRAN but i was not able to find a post or a package that could be used for an analysis like that.. I would appreciate your help... Kind regards to all R-helpers.. Achilleas.
n-dimensional(hypercube)distance calculation..
4 messages · achilleas.psomas@wsl.ch, Brian Ripley
On Thu, 14 Apr 2005 achilleas.psomas at wsl.ch wrote:
The `centers' are the means? by() can find the mean of multivariate data by group. And dist() finds Euclidean and other distances. However, the Jeffries-Matusita distance depends on covariance matrices, and 50 points in 100 dims are not enough to estimate one. Indeed my concern is that you have so few data that either the measurements are highly correlated (so you can just select a few) or your inferences will be suspect.
I am rather new in R so i would appreciate your help in my problem.. I have 3 types of vegetation (A,B,C),50 measurements per class and 100 variables per measurement.
It would be helpful to know how you have stored them.
I would like to perform seperability analysis between these classes meaning... a.)create the hypercube from these 100 variables
Which hypercube? If you mean the bounding box, use apply or lapply with range().
b.)"plot" the 50 measurements for each class and identify the position of the center of each class.. c.)calculate the distances between each class center using Euclidean, Jeffries-Matusita or other measures.
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
Hello R-Helpers.. Does anybody know if the Jeffries-Matusita distance is already applied in R code? Does it exist in any available package or has been ? I searched CRAN but couldnt find anything there.. Thanks in advance for your help.. AK
I believe not, but it would be a function of less than 10 lines, probably quicker to write than search for, find _and_ check what you found agrees with your definition (and BTW, more than one defn exists for it).
RSiteSearch("Matusita")
A search query has been submitted to http://search.r-project.org The results page should open in your browser shortly (in 2.1.0 beta) gave no matches, and it that is pretty comprehensive.
On Fri, 15 Apr 2005 achilleas.psomas at wsl.ch wrote:
Does anybody know if the Jeffries-Matusita distance is already applied in R code? Does it exist in any available package or has been ? I searched CRAN but couldnt find anything there..
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595