�减去行平均值），较小的那个数组的形状必须是(4,1)：</p>
<pre><code>In [87]: arr
Out[87]: 
array([[ 0.0009,  1.3438, -0.7135],
       [-0.8312, -2.3702, -1.8608],
       [-0.8608,  0.5601, -1.2659],
       [ 0.1198, -1.0635,  0.3329]])

In [88]: row_means = arr.mean(1)

In [89]: row_means.shape
Out[89]: (4,)

In [90]: row_means.reshape((4, 1))
Out[90]: 
array([[ 0.2104],
       [-1.6874],
       [-0.5222],
       [-0.2036]])

In [91]: demeaned = arr - row_means.reshape((4, 1))

In [92]: 