Remove non-driven shape keys for Blender 3+

remove_nondriven_shapekeys.py

bl_info = {
    "name": "Remove Non-driven Shape Keys",
    "description": "Removes any Shape Key which doesn't affect any vertices within tolerance.",
    "version": (1, 0),
    "blender": (3, 0, 0),
    "category": "Object",
}

import bpy
import numpy as np

def main_function(self, context):
    # Tolerance to small differences, change it if you want
    tolerance = 0.001

    assert bpy.context.mode == 'OBJECT', "Must be in object mode!"

    for ob in bpy.context.selected_objects:
        if ob.type != 'MESH': continue
        if not ob.data.shape_keys: continue
        if not ob.data.shape_keys.use_relative: continue

        kbs = ob.data.shape_keys.key_blocks
        nverts = len(ob.data.vertices)
        to_delete = []

        # Cache locs for rel keys since many keys have the same rel key
        cache = {}

        locs = np.empty(3*nverts, dtype=np.float32)

        for kb in kbs:
            if kb == kb.relative_key: continue

            kb.data.foreach_get("co", locs)

            if kb.relative_key.name not in cache:
                rel_locs = np.empty(3*nverts, dtype=np.float32)
                kb.relative_key.data.foreach_get("co", rel_locs)
                cache[kb.relative_key.name] = rel_locs
            rel_locs = cache[kb.relative_key.name]

            locs -= rel_locs
            if (np.abs(locs) < tolerance).all():
                to_delete.append(kb.name)

        for kb_name in to_delete:
            ob.shape_key_remove(ob.data.shape_keys.key_blocks[kb_name])

def draw_func(self, context):
    layout = self.layout
    obj = context.active_object

    row = layout.row()
    row.operator("object.remove_nondriven_shapekeys", text="Remove non-driven Shape Keys")

def register():
    bpy.types.DATA_PT_shape_keys.append(draw_func)
    bpy.utils.register_class(RemoveNonDrivenShapeKeysOperator)

def unregister():
    bpy.types.DATA_PT_shape_keys.remove(draw_func)
    bpy.utils.unregister_class(RemoveNonDrivenShapeKeysOperator)

class RemoveNonDrivenShapeKeysOperator(bpy.types.Operator):
    bl_idname = "object.remove_nondriven_shapekeys"
    bl_label = "Remove non-driven Shape Keys"
    
    def execute(self, context):
        main_function(self, context)
        return {'FINISHED'}