The first part is with loop, the second is vectorized. Maybe the three
rebin/reform can be done in one step? Anyway, what do you think?
pro test
x=[1.5,0.,0.5,1,1]
y=[1.,0,1,0,2]
TRIANGULATE, X, Y, triangles
s=size(triangles,/dimensions)
ctriangles=fltarr(s[0],s[1],3)
; 1. With loop
for i=0,s[1]-1 do begin
t=total((triangles eq triangles[0,i])+$
(triangles eq triangles[1,i])+$
(triangles eq triangles[2,i]),1)
ind=where(t eq 2,ct)
if ct ne 0 then ctriangles[*,i,0:ct-1]=triangles[*,ind]
endfor
; Third dimension gives the three contiguous neighbours
print, ctriangles
; 2. Vectorized
tr1=rebin(triangles,s[0],s[1],s[1])
block=tr1 eq
rebin(reform(triangles[0,*],1,1,s[1]),s[0],s[1],s[1],/sample )
block+=tr1 eq
rebin(reform(triangles[1,*],1,1,s[1]),s[0],s[1],s[1],/sample )
block+=tr1 eq
rebin(reform(triangles[2,*],1,1,s[1]),s[0],s[1],s[1],/sample )
block=total(block,1)
ind=where(block eq 2,ct)
x = ind mod s[1]
y = ind/s[1]
block=[transpose(y),triangles[*,x]]
; First column: triangle index
; Other three columns: vertices for a contiguous neighbour
print,block
end
On 23 Feb 2007 18:39:39 -0800, "Libertan" <tbethell@umich.edu> wrote:
> My question: For a given row in TR, let us say row n, how best to find
> all the other rows in TR which share two elements with row n? (The
> algorithm must of course reject row n in its resulting list). I have
> a rather inefficient solution, by far the slowest part of my code, and
> I'm desperate to increase its speed (hopefully ten fold). My routine
> uses one FOR loop (over cells n) within which are many WHERE commands
> (which search for neighbour candidates).
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
