Quickly add selected objects into empty group for every selected object

addToGroup.py

import re
import maya.cmds as mc
def addToGroup( *args ):
	post,replacePost,postIndex,dupIgnore = parseArgs( args ) 
	allObj = mc.ls( sl=1, l=1  )
	rootNode = [ a.rsplit('|',a.count('|')-1 )[0] if a.count('|')  > 1 else a for a in allObj  ]
	newHi = sum( ( [ k for k in mc.listRelatives( m, ad=1, typ='transform', f=1 ) ] + [m] if mc.listRelatives( m, ad=1, typ='transform', f=1 ) else [m] for m in list( set( rootNode ) ) ), [] )
	hiSel = [ x for x in newHi if x in allObj ]
	newNObjects = []
	for a in hiSel:
		parentObj = mc.listRelatives( a, p=1, f=1 )
		lookName = a.rsplit('|',1)[-1]
		if '_' + post not in lookName:
			lookName += '_' + post
		nums = re.findall(r'\d+', lookName)
		if postIndex <= len(nums) and postIndex:
			splt = re.split(r'(\d+)', lookName)
			count = int(splt[postIndex*2-1])
			splt[postIndex*2-1] = '%s'
			newName = ''.join(splt)
		else:
			newName = lookName + '%s'
			count = 0
		while mc.objExists( newName % str(count) ):
			count += 1
		if parentObj:
			grp = mc.duplicate( po=1, n=newName % str(count) )[0]
			newObject = a.replace( parentObj[0], parentObj[0] + '|' + grp )
		else:
			grp = mc.duplicate( po=1, n=newName % str(count) )[0]
			newObject = grp + a
		mc.parent( a, grp)
		replacedNewNObjects = [ x.replace( a, newObject ) if a in x else x for x in newNObjects ]
		newNObjects = replacedNewNObjects
		newNObjects.append( newObject )
	mc.select( newNObjects, r=1 )

def parseArgs( args ):
	post = ''
	replacePost = ''
	postIndex = 0
	dupIgnore = 1
	stringArgs = [ x for x in args if isinstance(x, basestring)]
	intArgs = [ x for x in args if type(x)==int ]
	if stringArgs:
		post = stringArgs.pop(0)
		if stringArgs:
			replacePost = stringArgs.pop(0)
	if intArgs:
		postIndex = intArgs.pop(0)
		if intArgs:
			dupIgnore = intArgs.pop(0)
	return post,replacePost,postIndex,dupIgnore

# Add postfix in quotes if you need
addToGroup( 'GRP',1 )