"No module named fenics" in FEniCS Docker image

[kevin bo]

Hello, 

I installed docker toolbox and installed fenics in the dockerquickstart terminal.

I this terminal I successfully run a Fenics docker image using "fenicsproject run". 

But when I want to run a script I get the error "no module named fenics" when I do "from fenics import * "

I have absolutly no idea why. Can you help me? 

I puts some sceenshot with the mail

Thank you

Kind regards 

[Jan Blechta]

Use Python 3. FEniCS does not support Python 2 any more.

Jan

[kevin bo]

Hello,

As proposed by Jan Blechta

[kevin bo]

Hello, 

As proposed by Jan Bletcha, I used Python3 instead of Python and the demo worked well. But I had a new problem when I tried to run my own code. It occured when I tried to define my  own user Expression. I made a quick exemple using the exemple of fenics tutorial ft01_poisson. Ones again I puts some sceenshots with the mail to show my error

Thank you

Kind regards 

The error :

File "/usr/local/lib/python3.5/dist-package/dolfin/function/expression.py" line 408, in __getattr

return self.parameters[name]

RecursionError : maximum recursion depth exceeded

The exemple : 

from __future__ import print_function

from fenics import *

from mshr import *

class UserExpression(Expression):

    def __init__(self, Parameter=1):

        self.Parameter = Parameter

        

    def eval(self, value, x):

        value[0] = self.Parameter*(1 + x[0]*x[0] + 2*x[1]*x[1])

    def value_shape(self):

        return (2,)

# Create mesh  

mesh = UnitSquareMesh(8, 8)

V = FunctionSpace(mesh, 'P', 1)

# Define boundary condition

u_D = UserExpression(Parameter=1)

#u_D = Expression('1 + x[0]*x[0] + 2*x[1]*x[1]', degree=2)

    

def boundary(x, on_boundary):

    return on_boundary

bc = DirichletBC(V, u_D, boundary)

# Define variational problem

u = TrialFunction(V)

v = TestFunction(V)

f = Constant(-6.0)

a = dot(grad(u), grad(v))*dx

L = f*v*dx

# Compute solution

u = Function(V)

solve(a == L, u, bc)

# Plot solution and mesh

plot(u)

plot(mesh)

# Save solution to file in VTK format

vtkfile = File('poisson/solution.pvd')

vtkfile << u

# Compute error in L2 norm

error_L2 = errornorm(u_D, u, 'L2')

# Compute maximum error at vertices

vertex_values_u_D = u_D.compute_vertex_values(mesh)

vertex_values_u = u.compute_vertex_values(mesh)

import numpy as np

error_max = np.max(np.abs(vertex_values_u_D - vertex_values_u))

# Print errors

print('error_L2  =', error_L2)

print('error_max =', error_max)

On Sat, Jul 14, 2018 at 3:42 PM, Jan Blechta <ble...@karlin.mff.cuni.cz> wrote:

[Jan Blechta]

Are you using FEniCS 2018.1.0? The tutorial has not been updated to
reflect recent changes in FEniCS interface. See
https://fenicsproject.org/docs/dolfin/dev/python/demos/biharmonic/demo_biharmonic.py.html?highlight=userexpression
how to use UserExpression.

Jan


On Wed, 25 Jul 2018 14:06:11 +0200

kevin bo <kevin....@gmail.com> wrote:

> Hello,

> As proposed by Jan Bletcha, I used Python3 instead of Python and the
> demo worked well. But I had a new problem when I tried to run my own
> code. It occured when I tried to define my own user Expression. I
> made a quick exemple using the exemple of fenics tutorial
> ft01_poisson. Ones again I puts some sceenshots with the mail to show
> my error Thank you
> Kind regards
>

> *The error :*

>
> File
> "/usr/local/lib/python3.5/dist-package/dolfin/function/expression.py"
> line 408, in __getattr return self.parameters[name]
> RecursionError : maximum recursion depth exceeded
>

> *The exemple : *

[kevin bo]

Hello, 

Firstly thank you very much for your quick answers.

I think I have the latest version because I reinstall everything when I had the error the fisrt time (3 weeks ago maybe).

I tried to use UserExpression instead of Expression and the error I get is the following (where UserExp is the class I have defiened)

File 'ft_01_poisson.py', line 37, in (module)

      bc =  DirichletBC(V, u_D, bondary)

File '/usr/loval/lib/python3.5/dist-packages/dolfin/fem/projection.py', line 129 in project 

      L = ufl.inner(w,v) * dx

File  '/usr/loval/lib/python3.5/dist-packages/ufl/operators.py' line 142 in inner

      if a.ufl_shape == () and b.ufl_shape ==():

File  '/usr/loval/lib/python3.5/dist-packages/ufl/coefficient.py' line 73 in ufl_shape

      return self._ufl_shape

AttributeError : 'UserExp' object has no attribute '_ufl_shape'

[Jan Blechta]

On Wed, 25 Jul 2018 14:50:58 +0200

kevin bo <kevin....@gmail.com> wrote:

> Hello,

> Firstly thank you very much for your quick answers.
> I think I have the latest version because I reinstall everything when
> I had the error the fisrt time (3 weeks ago maybe).
> I tried to use UserExpression instead of Expression and the error I
> get is the following (where UserExp is the class I have defiened)

You have to call the superclass constructor, see
https://fenicsproject.org/docs/dolfin/dev/python/demos/mixed-poisson/demo_mixed-poisson.py.html?highlight=userexpression

Jan

[kevin bo]

It work fine thank you very much !