How to use the pyvista.read function in pyvista

def test_multi_block_io(extension, binary, tmpdir):
    filename = str(tmpdir.mkdir("tmpdir").join('tmp.%s' % extension))
    multi = pyvista.MultiBlock()
    # Add examples
    multi.append(ex.load_ant())
    multi.append(ex.load_sphere())
    multi.append(ex.load_uniform())
    multi.append(ex.load_airplane())
    multi.append(ex.load_globe())
    # Now check everything
    assert multi.n_blocks == 5
    # Save it out
    multi.save(filename, binary)
    foo = pyvista.MultiBlock(filename)
    assert foo.n_blocks == multi.n_blocks
    foo = pyvista.read(filename)
    assert foo.n_blocks == multi.n_blocks

def test_read_uniform_grid_from_file():
    grid = pyvista.read(examples.uniformfile)
    assert grid.n_cells == 729
    assert grid.n_points == 1000
    assert grid.bounds == [0.0,9.0, 0.0,9.0, 0.0,9.0]
    assert grid.n_arrays == 2
    assert grid.dimensions == [10, 10, 10]

def test_read_rectilinear_grid_from_file():
    grid = pyvista.read(examples.rectfile)
    assert grid.n_cells == 16146
    assert grid.n_points == 18144
    assert grid.bounds == [-350.0,1350.0, -400.0,1350.0, -850.0,0.0]
    assert grid.n_arrays == 1

def test_vertice_cells_on_read(tmpdir):
    point_cloud = pyvista.PolyData(np.random.rand(100, 3))
    filename = str(tmpdir.mkdir("tmpdir").join('foo.ply'))
    point_cloud.save(filename)
    recovered = pyvista.read(filename)
    assert recovered.n_cells == 100
    recovered = pyvista.PolyData(filename)
    assert recovered.n_cells == 100

def test_save_uniform(extension, binary, tmpdir):
    filename = str(tmpdir.mkdir("tmpdir").join('tmp.%s' % extension))
    ogrid = examples.load_uniform()
    ogrid.save(filename, binary)
    grid = pyvista.UniformGrid(filename)
    assert grid.n_cells == ogrid.n_cells
    assert grid.origin == ogrid.origin
    assert grid.spacing == ogrid.spacing
    assert grid.dimensions == ogrid.dimensions
    grid = pyvista.read(filename)
    assert isinstance(grid, pyvista.UniformGrid)
    assert grid.n_cells == ogrid.n_cells
    assert grid.origin == ogrid.origin
    assert grid.spacing == ogrid.spacing
    assert grid.dimensions == ogrid.dimensions

def download_lobster():
    """Scan of a lobster from
        https://www.laserdesign.com/lobster-scan-data
    """
    url = "http://3dgallery.gks.com/2016/lobster/index2.php"
    filename, _ = _retrieve_file(url, 'lobster.ply')
    return pyvista.read(filename)

def download_blood_vessels():
    """data representing the bifurcation of blood vessels."""
    local_path, _ = _download_file('pvtu_blood_vessels/blood_vessels.zip')
    filename = os.path.join(local_path, 'T0000000500.pvtu')
    mesh = pyvista.read(filename)
    mesh.set_active_vectors('velocity')
    return mesh

# of files.
#
# Let's inspect where this downloaded our dataset:
path = os.path.join(pv.EXAMPLES_PATH, "blood_vessels")
print(os.listdir(path))

###############################################################################
print(os.listdir(os.path.join(path, "T0000000500")))

###############################################################################
# Note that a ``.pvtu`` file is available along side a directory. This
# directory contains all the parallel files or pieces that make the whole mesh.
# We can simply read the ``.pvtu`` file and VTK will handle putting the mesh
# together.
filename = os.path.join(path, "T0000000500.pvtu")
mesh = pv.read(filename)
print(mesh)

###############################################################################
# Plot the pieced together mesh
mesh.plot(scalars="node_value", categories=True)


###############################################################################
mesh.plot(scalars="density")

def download_face2():
    """Scan of a man's face from
        https://www.laserdesign.com/sample-files/mans-face/
    """
    url = "http://3dgallery.gks.com/2012/face/"
    filename, _ = _retrieve_file(url, 'man_face.stl')
    return pyvista.read(filename)