```python
import numpy as np
import porepy as pp

def add_data(gb, domain):
    for g, d in gb:
        # Assign permeability
        kxx = np.ones(g.num_cells) * 1e-9
        perm = pp.SecondOrderTensor(kxx)
        d[pp.PARAMETERS] = {"second_order_tensor": perm}
        
        # Assign apertures for fractures
        if g.dim < gb.dim_max():
            aperture = np.power(1e-4, gb.dim_max() - g.dim)
            d[pp.PARAMETERS]["aperture"] = aperture
        
        # Boundary conditions
        bc_faces = g.get_boundary_faces()
        bc_type = np.array(["dir"] * bc_faces.size)
        bc = pp.BoundaryCondition(g, faces=bc_faces, cond=bc_type)
        bc_values = np.zeros(g.num_faces)
        bc_values[bc_faces] = 1
        d[pp.PARAMETERS]["bc"] = bc
        d[pp.PARAMETERS]["bc_values"] = bc_values

def plot_over_line(gb, start_point, end_point, num_points, variable):
    line = np.linspace(start_point, end_point, num_points)
    values = []
    for pt in line:
        cell = pp.closest_cell(gb, pt)
        g, d = gb.cell_props(cell)
        values.append(d[pp.STATE][variable][cell])
    return line, values

tol = 1e-5
mesh_size = {"mesh_size_frac": 0.1, "mesh_size_min": 0.02, "mesh_size_bound": 0.1}
domain = {"xmin": 0, "xmax": 1, "ymin": 0, "ymax": 1}

csv_file = "path_to_csv_file.csv"
gb = pp.io.grid_bucket_from_csv(csv_file)
gb.compute_geometry()
gb.coarsen()
gb.assign_node_ordering()

add_data(gb, domain)

solver = pp.DualVEMMixDim(gb)
A, b = solver.matrix_rhs()
solution = solver.solve(A, b)

split_solution = pp.fvutils.split_dofs(gb, solution)
discharge, pressure = split_solution[0], split_solution[1]
pp.project_discharge(gb, discharge, "pressure", "flux")

pp.io.write_vtk(gb, "grid_bucket_output", data={"pressure": pressure, "flux": discharge})

bbox = np.array([[0, 1], [0, 1]])
num_points = 100
x_line = np.linspace(bbox[0, 0], bbox[0, 1], num_points)
y_line = np.linspace(bbox[1, 0], bbox[1, 1], num_points)

x_points = np.vstack((x_line, np.zeros(num_points))).T
y_points = np.vstack((np.zeros(num_points), y_line)).T

x_line, x_values = plot_over_line(gb, x_points[0], x_points[-1], num_points, "pressure")
np.savetxt("pressure_along_x.csv", np.vstack((x_line, x_values)).T, delimiter=",")

y_line, y_values = plot_over_line(gb, y_points[0], y_points[-1], num_points, "pressure")
np.savetxt("pressure_along_y.csv", np.vstack((y_line, y_values)).T, delimiter=",")

print("Diameter of the grid bucket:", gb.diameter())
print("Number of 2D cells:", gb.grids_of_dimension(2)[0].num_cells)
print("Number of 1D cells:", gb.grids_of_dimension(1)[0].num_cells)
```