Random Replace - Faster

from pymclevel import MCSchematic
from pymclevel import TileEntity
from pymclevel import TAG_Compound
from pymclevel import TAG_Short
from pymclevel import TAG_Byte
from pymclevel import TAG_String
import random

displayName = "Random Replace 2"

inputs = (
    ("Replace", "blocktype"),
    ("With", "blocktype"),
    ("Step", (2, 0, 500)),
    ("Any subtype", False)
)

def perform(level, box, options):
    mat1 = options["Replace"]
    mat2 = options["With"]
    step = options["Step"]
    subtype = options["Any subtype"]
    y = box.miny
    for x in xrange(box.minx, box.maxx):
        for z in xrange(box.minz, box.maxz):
            while y <= box.maxy:
                y = y + int(randomGen() * step) + 1
                if level.blockAt(x, y, z) == mat1.ID and (level.blockDataAt(x, y, z) == mat1.blockData or subtype):
                    level.setBlockAt(x, y, z, mat2.ID)
                    level.setBlockDataAt(x, y, z, mat2.blockData)
            y = box.miny
    level.markDirtyBox(box)
def randomGen():
    return random.random()