AttributeError:'numpy.ndarray'对象没有'median'属性

Question

我可以对numpy数组执行一些统计信息，但是“median”返回一个属性错误。当我做一个“dir（np）”时，我确实看到了列出的中值方法。

(newpy2) 7831c1c083a2:src scaldara$ python
Python 2.7.12 |Continuum Analytics, Inc.| (default, Jul  2 2016,   17:43:17) 
[GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)] on     darwin
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>>> import numpy as np
>>> print(np.version.version)
1.11.2
>>> a = np.array([1,2,3,4,5,6,7,8,9,10])
>>> print(a)
[ 1  2  3  4  5  6  7  8  9 10]
>>> print(a.min())
1
>>> print(a.max())
10
>>> print(a.mean())
5.5
>>> print(a.std())
2.87228132327
>>> print(a.median())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'numpy.ndarray' object has no attribute 'median'
>>> 

Answer 1

虽然numpy.ndarray有mean、max、std等方法，但它没有median方法。有关可用于ndarray的所有方法的列表，请参见^{} documentation for ^{}。

它可用作以数组为参数的函数：

>>> import numpy as np
>>> a = np.array([1,2,3,4,5,6,7,8,9,10])
>>> np.median(a)
5.5

正如您在the documentation for ^{}中看到的，ndarray.mean和np.mean是“等价函数”，所以这只是一个语义问题。