Updating cylinder's properties using a scipt I created cylinders using the bpy.ops.mesh.primitive_cylinder_add() command (I used this example). How can I update their radius (or any other property) using python script, instead of deleting the objects and recreate them? 
I'm using those cylinders to display connection between areas in the brain, as part of an addon I'm implementing. I want to let the user to pick the radius of the cylinders (for rendering purposes), or to automatically change them according to the connections' strength (which may vary).
An example using a custom property with an update method.

import bpy
from bpy.props import FloatProperty
context = bpy.context
scene = context.scene

def bond_strength(self, context):
    self.scale.x = self.scale.y =  self.bond_strength
    return None

# create a custom property on all objects
bpy.types.Object.bond_strength = FloatProperty(name="Strength",
                                               default = 1.0,
                                               precision = 4,
                                               update=bond_strength)

# adds a slider to UI object properties panel. # would be in a custom Panel
if True: # only need to run this once
    def show_strength(self, context):
        self.layout.prop(context.object, "bond_strength")
    bpy.types.OBJECT_PT_context_object.remove(show_strength) # put in unregister   
    bpy.types.OBJECT_PT_context_object.append(show_strength)

# add a primitive
bpy.ops.mesh.primitive_cylinder_add(radius=1.0)

#create more
cyl = context.active_object  # newly created cylinder

for i in range(4):
    cyl = cyl.copy()
    scene.objects.link(cyl)
    cyl.bond_strength *= 0.5
    cyl.location.x += 2