你的虚伪我赖的敷衍108433236
问题描述
在 numpy 中应用 sum 和 mean 时有没有办法避免使用特定值?
Is there a way to avoid using specific values when applying sum and mean in numpy?
例如，我想在计算结果时避免使用 -999 值.
I'd like to avoid, for instance, the -999 value when calculating the result.
In [14]: c = np.matrix([[4., 2.],[4., 1.]])
In [15]: d = np.matrix([[3., 2.],[4., -999.]])
In [16]: np.sum([c, d], axis=0)
Out[16]:
array([[ 7., 4.],
[ 8., -998.]])
In [17]: np.mean([c, d], axis=0)
Out[17]:
array([[ 3.5, 2. ],
[ 4. , -499. ]])
推荐答案
使用掩码数组:
>>> c = np.ma.array([[4., 2.], [4., 1.]])
>>> d = np.ma.masked_values([[3., 2.], [4., -999]], -999)
>>> np.ma.array([c, d]).sum(axis=0)
masked_array(data =
[[7.0 4.0]
[8.0 1.0]],
mask =
[[False False]
[False False]],
fill_value = 1e+20)
>>> np.ma.array([c, d]).mean(axis=0)
masked_array(data =
[[3.5 2.0]
[4.0 1.0]],
mask =
[[False False]
[False False]],
fill_value = 1e+20)
