How to load a .vtk file in a dolfin function?

Question

How can I load the data from a file 'velocity.pvd' to a
function u in order to use the ploting capabilities of dolfin?

Answer 1

Visualisation is best done in ParaView (www.paraview.org) - free to download.
DOLFIN can't read in pvd files.

Comments

Thank you for the answer!

What are the formats that dolfin imports to
a function? Is it possible to save the data
in one of this formats?

I am running some Dolfin exemples on Sage
Math Cloud. There isnt't ploting vtk available
on the browser. I just wan't to import a file to a
dolfin function of my Mac terminal and plot
it without external software...