Calculate cell interdistance from input coordinates.


        Parameters
        ----------
        x, y, z : numpy.ndarray
            xyz-coordinates of each cell-body.


        Returns
        -------
        min_cell_interdist : np.nparray
            For each cell-body center, the distance to nearest neighboring cell

def calc_min_cell_interdist(self, x, y, z):
        """
        Calculate cell interdistance from input coordinates.


        Parameters
        ----------
        x, y, z : numpy.ndarray
            xyz-coordinates of each cell-body.


        Returns
        -------
        min_cell_interdist : np.nparray
            For each cell-body center, the distance to nearest neighboring cell

        """
        min_cell_interdist = np.zeros(self.POPULATION_SIZE)

        for i in range(self.POPULATION_SIZE):
            cell_interdist = np.sqrt((x[i] - x)**2
                    + (y[i] - y)**2
                    + (z[i] - z)**2)
            cell_interdist[i] = np.inf
            min_cell_interdist[i] = cell_interdist.min()

        return min_cell_interdist