Python按指定列筛选数据

    import numpy as np
    
    a_ndarray = np.array(
    [
        [1, 3],
        [3, 4],
        [3, 4444],
        [1, 6],
        [8, 6],
        [10, 6]
    ]
    )
    
    # 按照第一列进行筛选，选中等于1的行
    a_1 = a_ndarray[np.where(a_ndarray[:, 0] == 1)]
    a_2 = np.compress(a_ndarray[:, 0] == 1, a_ndarray, axis=0)
    
    # 检查发现两种方法得到的结果一致
    check_1 = np.all(a_1 == a_2)
    
    # 按照第一列进行筛选，选中等于1或3的行
    a_3 = a_ndarray[
    np.where(
        (a_ndarray[:, 0] == 1) | (a_ndarray[:, 0] == 3)
    )
    ]
    a_4 = np.compress(
    (a_nd