[R] alpha shape function

2009-02-18 Thread Pedroso MOACIR
Hi all, I want to approximate te shape of an area defined by a set of points. The convex hull is not good enough, but I think that an alpha shape would be fine. I did an RSiteSearch(), google search, RSeek.org search, looked at the CRAN Views, but was unable do find a function in R that computes

[R] subscripting a one column matrix drops dimension

2008-10-21 Thread Pedroso MOACIR
Hi all, Why subscripting a one column matrix drops one dimension? > x<- matrix(rnorm(100), ncol=1) > str(x) num [1:100, 1] -0.413 -0.845 -1.625 -1.393 0.507 ... > str(x[20:30,]) num [1:11] -0.315 -0.693 -0.771 0.448 0.204 ... > str(x[20:30]) num [1:11] -0.315 -0.693 -0.771 0.448 0.204 ..