Hello, I am trying to write out multiple functions in the same file in dolfinx XDMFFile format. Please find MWE below. When I open the XDMF file in Paraview 5.12, I am only able to see the second function being plotted, (array for function 1 not available). I also tried the “Filters → Extract block” as suggested here: multiple functions but still only able to visualize function 1.

```
from mpi4py import MPI
import dolfinx as dlx
import numpy as np
comm = MPI.COMM_WORLD
rank = comm.rank
nproc = comm.size
msh = dlx.mesh.create_unit_square(comm, 10, 10, dlx.mesh.CellType.quadrilateral)
Vh_m = dlx.fem.FunctionSpace(msh, ("Lagrange", 1))
f1 = dlx.fem.Function(Vh_m,name='f1')
f1.interpolate(
lambda x: np.log(2 + 7 * (((x[0] - 0.5) ** 2 + (x[1] - 0.5) ** 2) ** 0.5 > 0.2))
)
f1.x.scatter_forward()
f2 = dlx.fem.Function(Vh_m,name='f2')
f2.interpolate(
lambda x: np.log(10 + 3* (((x[0] - 0.5) ** 2 + (x[1] - 0.5) ** 2) ** 0.5 > 0.2))
)
f2.x.scatter_forward()
with dlx.io.XDMFFile(
msh.comm,
"output.xdmf".format(nproc),
"w",
) as file:
file.write_mesh(msh)
file.write_function(f1, 0)
file.write_function(f2, 1)
```

Some other links which may have relevant information but I am not able to get it to work:

Hey all,
I am experiencing some issues trying to visualize vector fields in ParaView 5.11.1 when multiple functions are stored in a single XDMF file. Maybe this turns out to be a ParaView question, but my impression is that something is wrong with how I write the XDMF files.
Consider the following MWE that creates and writes 2 vector fields:
import dolfinx
import numpy as np
from dolfinx import fem, io
from mpi4py import MPI
from petsc4py import PETSc
mesh = dolfinx.mesh.create_unit_square(…
Time dependent: Time-dependent mesh using XDMF File in DOLFINx - #10 by rsz7ncf24p

Hi.

Welcome to the FEniCS community!

Changing `file.write_function(f2, 1)`

by `file.write_function(f2, 0)`

gives the desired result.

Consider the following MWE (adapted from your code):

```
from mpi4py import MPI
import dolfinx as dlx
import numpy as np
comm = MPI.COMM_WORLD
rank = comm.rank
nproc = comm.size
msh = dlx.mesh.create_unit_square(comm, 10, 10, dlx.mesh.CellType.quadrilateral)
Vh_m = dlx.fem.FunctionSpace(msh, ("Lagrange", 1))
f1 = dlx.fem.Function(Vh_m,name='f1')
f1.interpolate(
lambda x: np.sin(x[0]*x[1])
)
f1.x.scatter_forward()
f2 = dlx.fem.Function(Vh_m,name='f2')
f2.interpolate(
lambda x: 1/np.sqrt((x[0]-0.5)**2 + (x[1]-0.5)**2 + 1.)
)
f2.x.scatter_forward()
with dlx.io.XDMFFile(
msh.comm,
"outputmutiple.xdmf".format(nproc),
"w",
) as file:
file.write_mesh(msh)
file.write_function(f1, 0)
file.write_function(f2, 0)
```

Which produces

1 Like

Thank you so much for the quick help. It works now.