A = [[ 4  9]
     [15 19]
     [20 28]
     [31 37]
     [43 43]]
v =  [ 0  1  2  3 11 12 13 14 26 29 30 31 43]

[[20 28]
 [31 37]
 [43 43]]

import numpy as np
np.random.seed(0)

size = 32000
base_arr = np.arange(size)*10

t1 = np.random.randint(0,6, size)+base_arr
t2 = np.random.randint(5,10, size)+base_arr

A = np.vstack((t1,t2)).T
v = np.sort(np.random.randint(0,10,3*size)+np.repeat(base_arr,3))