numpy.setdiff1d

numpy.setdiff1d(ar1, ar2, assume_unique=False) [source]

Find the set difference of two arrays.

Return the unique values in ar1 that are not in ar2.

Parameters:	ar1 : array_like Input array. ar2 : array_like Input comparison array. assume_unique : bool If True, the input arrays are both assumed to be unique, which can speed up the calculation. Default is False.
Returns:	setdiff1d : ndarray 1D array of values in ar1 that are not in ar2. The result is sorted when assume_unique=False, but otherwise only sorted if the input is sorted.

See also

numpy.lib.arraysetops

Module with a number of other functions for performing set operations on arrays.

Examples

>>> a = np.array([1, 2, 3, 2, 4, 1])
>>> b = np.array([3, 4, 5, 6])
>>> np.setdiff1d(a, b)
array([1, 2])