On Tue, Mar 31, 2009 at 9:45 PM, Sean Law <magic...@hotmail.com> wrote:
> the performance is lightning fast. Can anybody help me improve the overall
> performance or suggest an alternative? Thanks in advance!
A kind of alternative would be to use a custom dihedral command, that
avoids evaluating selections:
def torsion(a, b, c, d):
l = (b - a).cross(c - b)
r = (d - c).cross(b - c)
a = degrees(l.angle(r))
if (l.cross(r) * (c - b)) < 0.0:
return -a
else:
return a
where a, b, c, and d are vector classes and 'cross' is defined as usual like:
def cross(self, other):
return Vector(self.y * other.z - self.z * other.y,
self.z * other.x - self.x * other.z,
self.x * other.y - self.y * other.x)
pymol has a vector class in the chempy package called 'cpv'.
gilleain
