�partition(arr, 3)，结果中的头三个元素是最小的三个，没有特定的顺序。numpy.argpartition与numpy.argsort相似，会返回索引，重排数据为等价的顺序：</p>
<pre><code>In [198]: indices = np.argpartition(arr, 3)

In [199]: indices
Out[199]: 
array([16, 11,  3,  2, 17, 19,  0,  7,  8,  1, 10,  6, 12, 13, 14, 15,  5,
        4, 18,  9])

In [200]: arr.take(indices)
Out[200]: 
array([-2.0016, -1.2962, -0.5557, -0.5194, -0.3718, -0.4386, -0.2047,
        0.2817,  0.769 ,  0.47