New fixed.angle() Function

(This article was first published on geomorph, and kindly contributed to R-bloggers)

Hello morphometricians,
Below you can find a new fixed angle function addressing the problem discovered by Fabio Machado in the morphmet mail archive. We will include this function in our next schedule update to geomorph.




if (length(dim(A))!=3){
stop("Data matrix 1 not a 3D array (see 'arrayspecs').") }
stop("Data matrix 1 contains missing values. Estimate these first(see 'estimate.missing').") }
n<-dim(A)[3]; k<-dim(A)[2]; p<-dim(A)[1]
if (k!=2){
stop("Method presently implemented for two-dimensional data only.")}
if (angle>pi*2){
stop("Additional angle must be specified in radians.")}
if (angle< -pi*2){
stop("Additional angle must be specified in radians.")}
for (i in 1:n){
angl[i]<- acos((A[angle.pts[1],,i]/sqrt(sum(A[angle.pts[1],,i]^2)))%*%(A[angle.pts[2],,i]/sqrt(sum(A[angle.pts[2],,i]^2))))
dev.angle<- (angl-mean(angl))+angle
if(A[angle.pts[1],1,1]<0){dev.angle<- -1*dev.angle}
for (i in 1:n){
r = matrix(c(cos(dev.angle[i]),-sin(dev.angle[i]),sin(dev.angle[i]),cos(dev.angle[i])),2)
A[rot.pts,,i] = A[rot.pts,,i]%*%r

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