[英]Comparing two Numpy Arrays and keeping non-equal vectors in a third array
I have two 2D arrays filled with vectors.我有两个用向量填充的二维数组。 I want to compare all the vectors of A to all the vectors in B and keep all the vectors of B that are unequal to the vectors in A. Like this on a small scale:
我想将 A 的所有向量与 B 中的所有向量进行比较,并保留 B 的所有向量不等于 A 中的向量。像这样在小范围内:
A = [[0,1,0], [1,1,0], [1,1,1]] A = [[0,1,0], [1,1,0], [1,1,1]]
B = [[0,0,0], [1,0,0], [0,1,0], [1,1,0], [1,1,1]] B = [[0,0,0], [1,0,0], [0,1,0], [1,1,0], [1,1,1]]
Result = [[0,0,0], [1,0,0]]结果 = [[0,0,0], [1,0,0]]
I am using numpy and cant seem to figure out an efficient way to do this.我正在使用 numpy 并且似乎无法找到一种有效的方法来做到这一点。 I have tried using two for loops which seems very ineffcient and I have tried to use a for loop, but this seems very inefficient:
我尝试使用两个 for 循环,这似乎非常低效,我尝试使用 for 循环,但这似乎非常低效:
for i in A:
for j in B:
if not np.all(A==B):
print(B)
and np.where, but that does not yield the right results.和 np.where,但这不会产生正确的结果。
for i in A:
np.where(A!=1, A, False)
This is probably easy for some people but I am very grateful for any advice.这对某些人来说可能很容易,但我非常感谢任何建议。
Kind regards,亲切的问候,
Nico尼科
If both arrays have a decent size, you can use broadcasting:如果两个数组的大小都合适,则可以使用广播:
A = np.array([[0,1,0], [1,1,0], [1,1,1]])
B = np.array([[0,0,0], [1,0,0], [0,1,0], [1,1,0], [1,1,1]])
out = B[(A!=B[:,None]).any(2).all(1)]
Output:输出:
array([[0, 0, 0],
[1, 0, 0]])
Alternatively, you can use python sets:或者,您可以使用 python 集:
a = set(map(tuple, A))
b = set(map(tuple, B))
out = np.array(list(b.difference(a)))
You can simply use a list comprehension:您可以简单地使用列表推导:
A = [[0,1,0], [1,1,0], [1,1,1]]
B = [[0,0,0], [1,0,0], [0,1,0], [1,1,0], [1,1,1]]
[x for x in B if x not in A]
#output
[[0, 0, 0], [1, 0, 0]]
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