DELDIR
This question should have been, in first instance, directed to me (the maintainer of the deldir package), rather than to the r-sig-geo list.
On 24/07/19 1:47 AM, PONS Frederic - CEREMA/DTerMed/DREC/SRILH wrote:
Dear all Sometines we are using the deldir function for squeletisation.
Had to Google this word. According to what I see it should be spelled "squelettisation" (with a double "t"). The English word is "skeletonisation", and this list is (for better or for worse) an English language list.
Since the last review, deldir stops in some shapefile because polygons
are too narrow. In the version berfore, there was no problems.
We have readed the " Notes on error messages" and the problem of
anticlockwise order of triangle is listed.
In the trifnd R function , the code is
# Check that the vertices of the triangle listed in tau are
# in anticlockwise order. (If they aren't then alles upgefucken
# ist; throw an error.)
call acchk(tau(1),tau(2),tau(3),anticl,x,y,ntot,eps)
if(!anticl) {
call acchk(tau(3),tau(2),tau(1),anticl,x,y,ntot,eps)
if(!anticl) {
call fexit("Both vertex orderings are clockwise. See help for
deldir.")
} else {
ivtmp = tau(3)
tau(3) = tau(1)
tau(1) = ivtmp
}
}
We don't understand why do not order the bad triangles into the good
order. Perhaps, if this problem appears, the beginning of the deldir
function is not good.
If someone can explain us.
The error message you quote indicates that *both* orderings are bad so something is toadally out of whack. It would be rash (and arrogant) for the software to fool around with the structure. In such situations the user should diagnose what is going wrong. If you cannot diagnose the problem, please send me a reprex and I will look into it. cheers, Rolf Turner
Honorary Research Fellow Department of Statistics University of Auckland Phone: +64-9-373-7599 ext. 88276