core/connectivity_restraint.py

This example shows how to use the ConnectivityRestraint to ensure that all the particles end up in a connected conformation following the optimization. One should also check out the IMP::atom::create_connectivity_restraint() helper functions.

## \example core/connectivity_restraint.py
# This example shows how to use the ConnectivityRestraint to ensure that
# all the particles end up in a connected conformation following the
# optimization. One should also check out the
# IMP::atom::create_connectivity_restraint() helper functions.

import IMP
import IMP.core
import IMP.algebra
import IMP.atom

m = IMP.kernel.Model()

# Put the parent particles for each molecule
hs = []

# create the molecules, with 5 particles for each of 10 molecules
for i in range(0, 10):
    pr = IMP.kernel.Particle(m)
    pr.set_name("root " + str(i))
    d = IMP.atom.Hierarchy.setup_particle(pr)
    for j in range(0, 5):
        p = IMP.kernel.Particle(m)
        p.set_name("fragment " + str(i) + " " + str(j))
        cd = IMP.atom.Fragment.setup_particle(p)
        d.add_child(cd)
        xd = IMP.core.XYZR.setup_particle(
            p, IMP.algebra.Sphere3D(IMP.algebra.Vector3D(3 * i, j, 0), 1))
    hs.append(pr)


ps = IMP.core.SphereDistancePairScore(IMP.core.HarmonicUpperBound(0, 1))
cps = IMP.core.ChildrenRefiner(IMP.atom.Hierarchy.get_traits())

# score based on the one closest particle from each set of balls
lrps = IMP.core.KClosePairsPairScore(ps, cps, 1)
# connect all 10 molecules together
cr = IMP.core.ConnectivityRestraint(m, lrps)
cr.set_particles(hs)
m.add_restraint(cr)

m.evaluate(False)