Efficient way to find overlapping of N rectangles

I am trying to find an efficient solution for finding overlapping of n rectangles where rectangles are stored in two separate lists. We are looking for all rectangles in listA that overlap with rectangles in listB (and vice versa). Comparing one element from the first list to second list could take immensely large amount of time. I am looking for an efficient solution.

I have two list of rectangles

rect = Rectangle(10, 12, 56, 15)rect2 = Rectangle(0, 0,1, 15)rect3 = Rectangle (10,  12, 56, 15)listA = [rect, rect2]listB = [rect3]

which is created from the class:

import numpy as npimport itertools as itclass  Rectangle(object):    def __init__(self, left, right, bottom, top):        self.left = left        self.bottom = right        self.right = bottom        self.top = top    def overlap(r1, r2):        hoverlaps = True        voverlaps = True        if (r1.left > r2.right) or (r1.right < r2.left):            hoverlaps = False        if (r1.top < r2.bottom) or (r1.bottom > r2.top):            voverlaps = False        return hoverlaps and voverlaps

I need to compare rectangle in listA to listB the code goes like this which is highly inefficient - comparing one by one

for a in it.combinations(listB):    for b in it.combinations(listA):        if a.overlap(b):

Any better efficient method to deal with the problem?