Selecting staggered vert/face from start and stop original selection

mayaVertFaceSelect.py

import re
import maya.cmds as cmds

def getSelectedInts():
    rx = re.compile(r'\[(\d+)\]$')
    
    intList = []
    sel = cmds.ls(sl=True)
    if not sel:
        return "", []
    
    obj = sel[0].split('.')[0]
    
    for v in cmds.ls(sl=True):
        search = rx.search(v)
        if search:
            num = search.group(1)
            intList.append( int(num) )

    return obj, intList


def getVertices():
    obj, vList = getSelectedInts()
    
    edges = cmds.polySelect(obj, q=True, shortestEdgePath=vList, asSelectString=True)
    cmds.select(edges, replace=True)
    lines = cmds.polyInfo(edgeToVertex=True)
    items = []
    for line in lines:
        vList = line.strip().split()[-2:]
        for v in vList:
            path = '%s.vtx[%s]' % (obj, v)
            if not path in items:
                items.append(path)
    
    return items
    
def getFaces():
    
    obj, fList = getSelectedInts()
    
    faces = cmds.polySelect(obj, shortestFacePath=fList, asSelectString=True)
    return faces


def main():
    # do selection
    selectBy = 2
    
    #items = getVertices()
    items = getFaces()
    
    cmds.select(clear=True)
   
    for i in xrange( 0, len(items), selectBy ):
        cmds.select(items[i], add=True)