# pip install instructions¶

Note: If you only plan to use the Fortran versions of the solvers (rather than PyClaw), and you run into problems with pip, then you might want to try Options for installing Clawpack Fortran codes.

## Quick Installation of PyClaw with pip¶

Please see Which Clawpack solver should I use? before installing, particularly if you are not sure whether you will be using the Fortran versions of the PDE solvers (Classic, AMRClaw, and GeoClaw) or the PyClaw version of the PDE solvers. See Installing Clawpack for other installation options.

Prerequisites: Before installing, check that you have the Installation Prerequisites.

If you only want to use PyClaw (and associated Python tools, e.g. VisClaw for visualization), then the simplest way to install Clawpack is via:

pip install --user clawpack


or, more specifically,

pip install --user clawpack==v5.9.0


or you can choose a previous version from the PyPi history.

However, note that this does not download the Fortran codes in a way that they can be used for Classic, AMRClaw, and GeoClaw.

If you think you might want to use the Fortran packages as well (Classic, AMRClaw, GeoClaw) and/or want easier access to the Python source code, it is recommended that you follow the pip instructions below.

## Quick Installation of all packages with pip¶

The recommended way to install the latest release of Clawpack, for using both PyClaw and the Fortran packages, is to use pip, e.g. with the following command (you might want to first read the notes below to see if you want to change anything in this command):

pip install --src=$HOME/clawpack_src --user -e \ git+https://github.com/clawpack/clawpack.git@v5.9.0#egg=clawpack-v5.9.0 \ --use-deprecated=legacy-resolver  Notes: • With older versions of pip, the flag –use-deprecated=legacy-resolver may not be recognized and is not needed. • Using pip to install will also check some python Installation Prerequisites and may update these on your system, and will use f2py to convert Fortran Riemann solvers to Python versions. See installing_options if you want more control. • This will download Clawpack (via a git clone) into the directory$HOME/clawpack_src/clawpack-v5.9.0. The top installation directory can be changed by modifying the --src target (or omit this part to put it in your current working directory). If you have already downloaded Clawpack via a different mechanism then see Using pip to install a different version rather than using the above command.

• See Clawpack components for a list of what’s included in this top level directory.

• The --user flag is necessary if you are installing on a shared computer where you do not have root access. If you do have root access and want it to be available to all users, you can omit this flag. See notes below for more information.

• The -e flag makes it an “editable” install, leaving the source code in place and allowing you to modify it if desired. (Otherwise, by default, pip would move the python code to some site-packages directory and delete everything else.)

• In order to use the Fortran codes within Clawpack (classic, amrclaw, or geoclaw), you should then set the environment variable CLAW to point to the clawpack-v5.9.0 directory within the installation directory $HOME/clawpack_src, and FC to point to the desired Fortran compiler, e.g. in the bash shell: export CLAW=$HOME/clawpack_src/clawpack-v5.9.0
export FC=gfortran

• You may want to set CLAW even if you are only using PyClaw, since $CLAW is sometimes used in this documentation to indicate the top level of the Clawpack source directory structure. Installing with pip also compiles Riemann solvers written in Fortran for use in PyClaw. If you get a Fortran error message when installing, see Setting the Fortran compiler to be used by f2py (pip). See Set environment variables for more information, and Python path if you are having problems with importing Python modules. ### Next steps:¶ Once Clawpack is installed, you can go to one of the following pages to get started: ### Using pip to install a different version¶ Using pip to download and install actually clones Git repositories from https://github.com/clawpack/clawpack. If you are comfortable with Git you can use the same top repository to update Clawpack or switch to other versions. However, if you have made any changes to files that are tracked by Git in this set of directories and then try to update or check out other branches, you may run into merge conflicts. Instead, you can always install another branch by doing a new pip install into a different subdirectory of clawpack_src, e.g. export CLAW_VERSION=v5.3.1 # used several places in next commands pip install --src=$HOME/clawpack_src --user -e \
git+https://github.com/clawpack/clawpack.git@$CLAW_VERSION#egg=clawpack-$CLAW_VERSION
export CLAW=$HOME/clawpack_src/clawpack-$CLAW_VERSION


If this version doesn’t already exist on your computer then it will clone the necessary repositories.

If you already have a different version of Clawpack in some directory obtained by any means (e.g. from a tarfile), then you can set the paths properly via:

export CLAW=/full/path/to/desired/version/of/clawpack
cd $CLAW pip install --user -e . # note trailing dot indicating "this directory"  See Python path if you are having problems with the wrong version being imported. ### Experimenting with code in the examples directories¶ We suggest that if you want to experiment extensively with examples or modify an example to solve your own problem, you first copy a directory out of the source code tree to a different location, in order to minimize confusion if you later want to update to a different version of clawpack. See Creating a new application directory for more details. If you want to check out the master branch of the clawpack repositories or work with other development versions, see Installation instructions for developers. ### Troubleshooting pip install¶ In case you run into problems with pip install or with changing version, here are some tips: • The -e flag (“editable”) results in the the source code remaining in the directory$CLAW, which includes all the Fortran packages as well as Python source.

• When the –user flag is omitted, the pip install will modify a system-wide file easy-install.pth to add the path. This requires root permission. When the –user flag is used, this path will instead be added to an easy-install.pth file that is within your user directory structure. See Python path for information on finding these files.

• If you use pip to install or switch versions then you should not set the environment variable PYTHONPATH. See Python path for more information.

• If you wish to point to a different version of the Clawpack Python tools, you need to rerun pip install (or use pip uninstall clawpack to remove clawpack from the search path controlled by pip).

• If you get a Fortran error message when installing, see Setting the Fortran compiler to be used by f2py (pip).

If you cannot get this to work, consider other Installing Clawpack and raise an issue to let us know what went wrong.