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[Jan Stránský <question667571@xxxxxxxxxxxxxxxxxxxxx>]

Question #667571 on Yade changed:
https://answers.launchpad.net/yade/+question/667571

    Status: Open => Answered

Jan Stránský proposed the following answer:
Hi Amauri,

please define more "a sphere pack". Do you mean loose packing like
SpherePack.makeCloud would generate? I assume so for the rest of the
answer

you can use "Python reimplementation" of SpherePack.makeCloud [1]:

###
import random
from yade import pack

def myMakeCloud(mn,mx,rMin,rMax,num,maxTry=1000,seed=0):
   random.seed(seed)
   mn = Vector3(mn)
   mx = Vector3(mx)
   size = mx-mn
   rnd = random.random
   ret = []
   for i in xrange(num):
      r = rMin + (rMax-rMin)*pow(-0.15 * log(1-rnd()), 1./0.75)
      for t in xrange(maxTry):
         c = Vector3([mn[axis] + r + (size[axis]-2*r)*rnd() for axis in (0,1,2)])
         packSize = len(ret)
         overlap = False
         for pc,pr in ret:
            if pow(pr+r,2) >= (pc-c).squaredNorm():
               overlap = True
               break
         if not overlap:
            ret.append((c,r))
            break
      if t == maxTry:
         print "WRNING: Exceeded {} tries to insert non-overlapping sphere to packing. Only {} spheres were added, although you requested {}.".format(maxTry,i,num)
   return pack.SpherePack(ret)

sp = myMakeCloud((0,0,0),(10,10,10),1,2,100)
sp.toSimulation()
O.step()
###

cheers
Jan

[1] https://github.com/yade/trunk/blob/master/pkg/dem/SpherePack.cpp#L86

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