col0_mask = np.abs(groupCoords[:, (0), (None)] - Arr[:, (0)]) <= 1
col1_mask = np.abs(groupCoords[:, (1), (None)] - Arr[:, (1)]) <= 1
out = groupCoords[(col0_mask & col1_mask).any(1)]
Проверка наличия смежных значений в матрице Numpy