Hi Michelle,

One problem might be misinterpreting what R displays when you use a function 
rather than what R might save as an object if you create an object based on the 
function.

For example, you could input the following

gpagen(mylandmarks, curves = mycurves, PrinAxes = T)

and R would return presumably return the landmarks and centroid sizes… up to a 
point where it might stop the display because of lots of values.  Alternative, 
and preferably (and maybe what you did, but you did not specify), if you input

mygpa <- gpagen(mylandmarks, curves = mycurves, PrinAxes = T)

Then R would return nothing, but it should list your Csize if you ask it to, 
i.e.,

mygpa$Csize

I’m not sure what you mean by "similar unsatisfactory results”.  Unsatisfactory 
because the module produces no results or because it produces results that are 
equally unsatisfying?

If you want a DIY approach, you can use mshape() to get the consensus 
configuration, subtract this from your landmarks, square the residuals, sum 
them by configuration and take the square root of the sum, by configuration.

Cheers -Mike

Michael Collyer

Assistant Professor
Department of Biology
Western Kentucky University
1906 College Heights Blvd. #11080
Bowling Green, KY 42101-1080
Phone: 270-745-8765; Fax: 270-745-6856
Email: [email protected]<mailto:[email protected]>

On Dec 4, 2014, at 5:31 PM, Michelle Singleton 
<[email protected]<mailto:[email protected]>> wrote:


Hello All,

I am having trouble with the gpagen  module in Adam et al.'s Gemorph package, 
and I am hoping someone here may have encountered the same problem or have some 
insight into my problem.I am applying gpagen to execute GPA with sliding 
surface semilandmarks (bending energy criterion). I am running the most recent 
versions of both R and Geomorph.

According to the documentation, gpagen should return a list comprising 1) 
$coords: the aligned coordinate matrix and  2)  $Csize: a vector of centroid 
sizes. Instead, it is returning aligned, slid configurations in the same 3D 
array format (p, k, n) as the infile (generated using readland.nts) but no 
centroid size vector.

I have compared the pre- and post-slide configurations to confirm that sliding 
is occurring. I have tried running the csize module separately and gotten 
similar unsatisfactory results. Can anyone explain why I am getting partial 
output or recommend a fix or workaround?

Many, many thanks,

Michelle Singleton
[email protected]<mailto:[email protected]>




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