Transfer shader assignation (render layers)

gistfile1.py

import maya.cmds as cmds

def getSGsFromMaterial(shader):
    if cmds.ls(shader, materials=True):
        nodes = [i.split('.')[0] for i in cmds.connectionInfo(shader +'.outColor', destinationFromSource=True)]  # Faster than cmds.listConnections(shader, type="shadingEngine")
        shadingGroups = [i for i in nodes if cmds.nodeType(i) == 'shadingEngine']
        return shadingGroups
    return []

def getShaderAssignation(shader):
    shadingGroups = getSGsFromMaterial(shader) # Add checks?
    if shadingGroups:
        return cmds.sets(shadingGroups, query=True) or []
    return []

# Step one, select renderLayer
shaders = cmds.ls(materials=True)
assignations = {}
for shader in shaders:
    assignations[shader] = getShaderAssignation(shader)

# Step two, select masterLayer
for shader, assignation in assignations.iteritems():
    try:
        cmds.select(assignation)
        cmds.hyperShade(assign=shader)
    except Exception, e:
        print e
        print shader
        print assignation
        print '\n'