How to output data in formats other than pvd?

[Alpha-Legion]

For example, I want to output coordinates of vertices or the solution data.

[dham]

It rather depends on what you want to do with that data. We can also output to PETSc's HDF 5 format, but that's not all that useful for external consumption. Can you be a bit more specific about what specifically you want to export and for what purpose?

[Alpha-Legion]

Sorry for the unclear description. Since I am not familiar with Firedrake and VTK, I was intended to export the resulted data in my familiar formats, so that I can do the further computations and processing with my familiar tools.
But after this post, I found function.dat.data, which gives me the numpy data. So the problem has been solved.