Create a conda_ environment

Use one of the following methods to create a self-contained conda_ environment and then download and populate the environment with the prerequisites for :term:`FiPy` from the conda-forge_ channel at https://anaconda.org. See this discussion of the merits of and relationship between the different methods.

• Conda_ environment files

  This option is the most upgradable in the future and probably the best for development.

  $ conda env create --name <MYFIPYENV> \
      --file environments/<SOLVER>-environment.yml
  

  Note

  You can try to include multiple solver suites using conda env update, but be aware that different suites may have incompatible requirements, or may restrict installation to obsolete versions of Python. Given that :term:`FiPy` can only use one solver suite during a run, installing more than one solver in an environment isn't necessary.

  Attention!

  Successively updating an environment can be unpredictable, as later packages may conflict with earlier ones. Unfortunately, conda env create does not support multiple environment files.

  Alternatively, combine the different :file:`environments/<SOLVER>-environment.yml` files you wish to use, along with environment.yml files for any other packages you are interested in (conda-merge may prove useful). Then execute:

  $ conda env create --name <MYFIPYENV> --file <MYMERGEDENVIRONMENT>.yml
  

• conda-lock lockfiles

  This option will pin all the packages, so is the most reproducible, but not particularly upgradable. For most, this is the safest way to generate a FiPy environment that consistently works.

  $ conda-lock install --name <MYFIPYENV> \
      environments/locks/conda-<SOLVER>-lock.yml
  

  or, to be really explicit (and obviating the need for conda-lock):

  $ conda create --name <MYFIPYENV> \
      --file environments/locks/conda-<SOLVER>-<PLATFORM>.lock
  

• Directly from conda-forge_, picking and choosing desired packages

  This option is the most flexible, but has the highest risk of missing or incompatible packages.

  e.g.:

  $ conda create --name <MYFIPYENV> --channel conda-forge \
      python=3 numpy scipy matplotlib-base future packaging mpich \
      mpi4py petsc4py mayavi "gmsh <4.0|>=4.5.2"
  

  or:

  $ conda create --name <MYFIPYENV> --channel conda-forge \
      python=2.7 numpy scipy matplotlib-base future packaging \
      pysparse mayavi "traitsui<7.0.0" "gmsh<4.0"
  

  Attention!

  Bit rot has started to set in for Python 2.7. One consequence is that :class:`~fipy.viewers.vtkViewer.VTKViewer`s can raise errors (probably other uses of :term:`Mayavi`, too). Hence, the constraint of "traitsui<7.0.0".