How to check if a number is in a tensor or not?

1

How to check if the number 1 is in torch.tensor([1, 2, 3])?

2 
import torch
a = torch.arange(3)
b = a + 3
print((a == 1).nonzero().numel() > 0) # 1 is in a -> true
print((b == 1).nonzero().numel() > 0) # 1 is in b -> false
3

Thank you for your answer, I understand.