import numpy as np 

arr = np.array([[0, 0, 1, 1, 1],
                [0, 0, 1, 2, 2],
                [0, 0, 2, 2, 2],
                [3, 3, 3, 4, 4],
                [3, 3, 3, 4, 4]])

def remove_runs(arr):
    # 沿着行方向(diff(axis=1))比较相邻元素
    # 参考numpy handbook
    runs = np.where(np.diff(arr, axis=1) != 0)

    # 把相对于arr索引运行的每一个开头和末尾
    # 拼接起来成一个形如`(start, end)`的元组
    runs = np.c_[runs[0], runs[1], np.full(len(runs[0]), False)]
    runs = np.vstack(([0,0,False], runs, [arr.shape[0], arr.shape[1], False]))

    # 遍历runs列表
    for i in range(len(runs)-1):
        # 把运行中的元素提取出来
        start = (runs[i][0], runs[i][1])
        end = (runs[i+1][0], runs[i+1][1])
        run = arr[start[0]:end[0], start[1]:end[1]]

        # 如果运行不全是一个值，就标记为删除
        if run.size > 1 and not np.all(run == run[0]):
            runs[i][2] = True

    # 删除被标记的运行，返回新的数组
    mask = np.logical_not(runs[:,2])
    return arr[mask[:,:-1]]

new_arr = remove_runs(arr)
print(new_arr)

array([[0, 2],
       [0, 2],
       [3, 4],
       [3, 4]])