Script: Select Shape Key Vertices - BadDogSkyrim/PyNifly GitHub Wiki
""" Select vertices affected by the current shape key """
import bpy
import math
bpy.ops.object.mode_set(mode = 'EDIT')
bpy.ops.mesh.select_mode(type="VERT")
bpy.ops.mesh.select_all(action = 'DESELECT')
bpy.ops.object.mode_set(mode = 'OBJECT')
active_k = bpy.context.object.active_shape_key
kb = bpy.context.object.data.shape_keys.key_blocks[active_k.name]
for vb, vk in zip(bpy.context.object.data.vertices, active_k.data):
if (vb.co-vk.co).length > 0.0001:
vb.select = True
bpy.ops.object.mode_set(mode = 'EDIT')