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
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