nodes that are the highest level amongst the selected objects

highestObjInHierarchy_v01_002_20160917.py

from pymel.core import *
import random

def highestObjInHierarchy(objsList=[]):
    '''
    This function returns nodes at the highest level within the pass-in list of objects.
    This is accomplished by searching upwards through all selected nodes 
    to find the nodes that have parents that are not within the selection.
    
    objsList - a list of maya nodes. must be DAG nodes that belong to the scene hierarchy
    
    return - <list> the nodes that are the highest level of the selected objects
    '''
    random.shuffle(objsList)
    topLevelRefChildren = []
    if not objsList:
        print 'highestObjInHierarchy: nothing in list'
        return []
    for node in objsList:
        # print 'node is',node
        tmpParent = [x for x in listRelatives(node,p=True)]
        # print 'tmpParent is', tmpParent
        if tmpParent == []:
            # print node,'is the highest in referenced objects. breaking out of for loop'
            if node not in topLevelRefChildren:
                topLevelRefChildren.append(node)
            continue
        if tmpParent[0] not in refChildren:
            # print node,'is the highest in referenced objects'
            if node not in topLevelRefChildren:
                topLevelRefChildren.append(node)
    return topLevelRefChildren

# print highestObjInHierarchy([x for x in ls(type='reference')[0].referenceFile().nodes() if 'transform' in nodeType(x, i=True)])
print highestObjInHierarchy(ls(sl=True))