将logical_and 与列表列表一起使用

Question

Suppose I have the following two lists:

l = [[], [1]]
m = [0, 1]

If I check to see if elements are in a list:

>>> np.array(m[1]) == 1
True
>>> 1 in np.array(l)[1]
True

This works as expected.

However, if I use the numpy logical_and operator, this fails:

>>> np.logical_and(np.array(m) == 1, 1 in np.array(l))
array([False, False])

Why are both positions in the array being evaluated as False ?

The goal is to evaluate lists of these forms element-wise. And, as per the documentation, np.logical_and is used to "Compute the truth value of x1 AND x2 element-wise."

Since l is a list of lists, I am using the in operator to test the element-wise comparisons.

Thus, I expect the output of >>> np.logical_and(np.array(m) == 1, 1 in np.array(l))

to be

array([False, True])

after all, [1] is just an element in np.array(l) :

>>> for i in np.array(l):
...     print(i)
...
[]
[1]

Answer 1

So just analyzing your code

np.array(m) == 1 
>>> [False  True]
1 in np.array(l)
>>> False

You're basically comparing False with [False True]

Update

If you want the output to be [False True] then you should use logical_or instead.