def __init__(self, cities, **kwargs):
        """
        A two-dimensional traveling salesman problem (TSP)

        Parameters
        ----------
        cities : numpy.array
            The cities with 2-dimensional coordinates provided by a matrix where city is represented by a row.

        """
        n_cities, _ = cities.shape

        self.cities = cities
        self.D = cdist(cities, cities)

        super(TravelingSalesman, self).__init__(
            n_var=n_cities,
            n_obj=1,
            xl=0,
            xu=n_cities,
            vtype=int,
            **kwargs
        )

        A two-dimensional traveling salesman problem (TSP)

        Parameters
        ----------
        cities : numpy.array
            The cities with 2-dimensional coordinates provided by a matrix where city is represented by a row.

        
pymoo/problems/single/traveling_salesman.py