I'm controlling Blender's shapekey in the following Python script.

This still works fast enough, but is there any low layer code that works faster?

import bpy
selectList = bpy.context.selected_objects

if selectList[0].data.shape_keys:
    for block in selectList[0].data.shape_keys.key_blocks:
        block.value = 0.5

1 Answer 1



To avoid looping over collection and setting a property value per item can instead use collection.foreach_set(property_name, values) [Find numerous links re this']

The values list is a flat list, eg if the property uv for example is a vector then the list

values = [u0, v0, u1, v1, ...., un, vn] 

For keyblock values

import bpy

context = bpy.context

ob = context.object
me = ob.data
sks = me.shape_keys

if sks:
    vals = (0.5, ) * len(sks.key_blocks)
    sks.key_blocks.foreach_set("value", vals)
  • $\begingroup$ Great! Is there a way to avoid the assignment if, for example, I don't want to assign a value to the third value of key_blocks? Is there any way to have a list of [smile_L,eyeClose_L,smile_R,,eyeClose_R] and ignore smile_R? $\endgroup$
    – taichi
    Commented Aug 19, 2021 at 22:00
  • 1
    $\begingroup$ Can load the current values into a flat list with foreach_get eg blender.stackexchange.com/questions/1412/… $\endgroup$
    – batFINGER
    Commented Aug 20, 2021 at 3:15

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