In Python, how do I find the elements in array B that are not in array A?

Question

I'm trying to find the difference between the 2 arrays

arrayA = np.array(['A1', 'A2', 'A3'])
arrayB = np.array(['A1', 'A2', 'A3', 'A4', 'A5', 'A6'])

I'm trying to get

difference = ['A4', 'A5', 'A6']

How can I do this? Thank you.

Answer 1

Use numpy's setdiff:

np.setdiff1d(arrayA, arrayB)

Also - is there any special reason for which this needs to be a numpy array? You could simply use sets and then the minus operator: set(arrayA) - set(arrayB)

Answer 2

[i for i in arrayB if i not in arrayA]