问题描述
我有13 Python的numpy的数组：
I have 13 python NumPy arrays:
obj_1=np.array([784,785,786,787,788,789,790,791,792])
obj_2=np.array([716,717,718,730,731,732,721,722,724,726,727])
obj_3=np.array([658,659,660,661,662,663,664,665])
obj_4=np.array([581,582,583,589,590,591,595,597,598,599,601,605,606,613,614])
obj_5=np.array([533,534,535,536,537])
obj_6=np.array([464,469,472,474])
obj_7=np.array([406,409,411,412])
obj_8=np.array([345,346,347,349])
obj_9=np.array([277,278,281,282,283,284,288,296])
obj_10=np.array([217,219,220,223,224])
obj_11=np.array([154,155,156,157,158,159,160,161])
obj_12=np.array([91,92,93,94,95,96,97])
obj_13=np.array([28,29,30,31,32,33,34])
然后下面的循环：
Then the following loop:
for i in [obj_1, obj_2, obj_3, obj_4, obj_5, obj_6, obj_7, obj_8, obj_9, obj_10, obj_11, obj_12, obj_13]:
print i in [obj_1, obj_2, obj_3, obj_4, obj_5, obj_6, obj_7, obj_8, obj_9]
我希望这样的输出：
I would expect this output:
True
True
True
True
True
True
True
True
True
False
False
False
False
相反，我得到一个错误如下：
Instead I get the following with an error:
True
True
True
True
True
True
Traceback (most recent call last):
File "<ipython-input-221-c03c1ef308c6>", line 16, in <module>
print i in [obj_1, obj_2, obj_3, obj_4, obj_5, obj_6, obj_7, obj_8, obj_9]
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()
我测试了相同的名称和相同的循环不同的阵列;他们生产的任何错误。
I tested different arrays with the same names and the same for loop; they produced no error.
这似乎是问题出在阵列中的内容，但我想不通的地方。
It seems like the problem lies in the content of the arrays, but I couldn't figure out where.
有没有人有一个想法，为什么出现这种情况？
Does anyone have an idea why this happens?
推荐答案
当你做 OBJ在列表蟒蛇比较 OBJ 与每个列表的成员的平等。问题是，在numpy的平等经营者不以一致的方式行事。例如：
When you do obj in list python compares obj for equality with each of the members of list. The problem is that the equality operator in numpy doesn't behave in a consistent way. For example:
>>> obj_3 == obj_6
False
因为他们有不同的长度，一个布尔返回。
because they have different lengths, a boolean is returned.
>>> obj_7==obj_6
array([False, False, False, False], dtype=bool)
，因为它们具有相同的长度，所述阵列进行比较元件明智并返回numpy的数组。在这种情况下，真值是不确定的。它看起来像这样奇怪的行为是要。
正确的方式做这将是单独每对例如使用的：
The correct way to do it would be to compare individually each pair of arrays using for example numpy.array_equal:
for i in [obj_1, obj_2, obj_3, obj_4, obj_5, obj_6, obj_7, obj_8, obj_9, obj_10, obj_11, obj_12, obj_13]:
print any(np.array_equal(i, j) for j in [obj_1, obj_2, obj_3, obj_4, obj_5, obj_6, obj_7, obj_8, obj_9])
让你：
True
True
True
True
True
True
True
True
True
False
False
False
False
这篇关于检查是否数组是阵列的列表元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！