-------- Original Message -------- Subject: Re: new topic: when R becomes a nightmare Date: Thu, 1 Sep 2011 13:36:47 -0400 From: Carmelo Fruciano <[email protected]> To: [email protected] morphmet <[email protected]> ha scritto:
-------- Original Message -------- Subject: new topic: when R becomes a nightmare Date: Thu, 01 Sep 2011 16:40:54 +0200 From: MARIE CACHERA <[email protected]> Organization: IFREMER To: [email protected] dear morpho boss I am using the "shapes" package in R, and I am pretty lost actually. Everything I found about morphometrics analysis always speaks about "warp" (partial warp, principal warp, relative warp ...). the thing is, i don't get where are all these "warps" in the output of procGPA? I am probably dumb but I simply don't get it, and as I am the only one in my lab to do GPA, I feel a little bit alone (and even worth, i'm french, which make statistics even more harder for me when it's not written in my mother tongue). Hope someone can help me :)
Dear Marie, it sounds like R itself is not the problem. Maybe you're not still very familiar with geometric morphometrics terminology. Good starters might be: - this page http://life.bio.sunysb.edu/morph/glossary/gloss1.html - the book Zelditch, M. L., D. L. Swiderski, H. D. Sheets, and W. L. Fink. 2004. Geometric Morphometrics for biologists: a primer. Elsevier - this paper http://life.bio.sunysb.edu/morph/review/review.html Unfortunately, I am not very familiar with R (I keep saying myself that I should start using it sooner or later but I never do it, preferring usually MATLAB). However, from what I gather reading http://www.oga-lab.net/RGM2/func.php?rd_id=shapes:procGPA in the R function procGPA there is the option to perform a PCA on procustes residuals and obtaining PC scores, which is what one might call "relative warps scores" (well, not exactly but it should be numerically the same thing). However, given my lack of experience with R, please don't take what I say for granted and confirm it with someone who uses R for geometric morphometrics! Best wishes Carmelo -- Carmelo Fruciano Dipartimento di Biologia University of Catania Tel. +39 095 7306023 Cell. +39 349 5822831 e-mail [email protected] http://www.fruciano.it/research/ ---------------------------------------------------------------- Universita' di Catania - A.P.Se.Ma. Servizio di Posta Elettronica
