Test whether each element of a 1D array is also present in a second array.
Returns a boolean array the same length as ar1 that is True where an element of ar1 is in ar2 and False otherwise.
Parameters :  ar1 : (M,) array_like
ar2 : array_like
assume_unique : bool, optional


Returns :  in1d : (M,) ndarray, bool

See also
Notes
in1d can be considered as an elementwise function version of the python keyword in, for 1D sequences. in1d(a, b) is roughly equivalent to np.array([item in b for item in a]).
New in version 1.4.0.
Examples
>>> test = np.array([0, 1, 2, 5, 0])
>>> states = [0, 2]
>>> mask = np.in1d(test, states)
>>> mask
array([ True, False, True, False, True], dtype=bool)
>>> test[mask]
array([0, 2, 0])