====== Python ======
In this system, you can install [[https://github.com/pyenv/pyenv|pyenv]] in the user's environment by executing the following script.\\
Python version control is possible with pyenv. Please see below for details.\\
\\
===== Setup pyenv environment =====
Execute the following command to install pyenv in your home directory on super and gpu.\\
<code>$ bash /work/app/pyenv/pyenv-setup-20210617.bash</code>
\\
After executing the installation script, a file called bash_env will be generated in the current directory.\\
To load pyenv by default, copy the contents to ~/.bash_profile with the following command.\\
<code>$ cat bash_env >> ~/.bash_profile</code>
\\
After installing pyenv, log out from the front end node once, and then log in again.
\\
===== Basic usage of pyenv =====
==== Install Python ====
<code>
$ pyenv install --list ←View available Python versions
・・・・
$ pyenv install 3.7.8←Install Python 3.7.8
</code>
\\
==== Switch python versions ====
<code>
$ pyenv versions ←Check the installed version
* system (set by /home/userA/.pyenv/version)
  3.7.8
$ pyenv global 3.7.8 ←Switch to Python 3.7.8
$ python --version 
</code>
\\
You can also add packages using pip.\\ 
For more detailed usage, please check the pyenv documentation etc. \\
\\
Simple Python version management\\
[[https://github.com/pyenv/pyenv]]
\\
\\
===== How to run Python =====
When you execute Python programs with high load, **please use computing nodes** instead of front end nodes.\\

==== Example job scripts ====
=== Large-Scale Parallel Computing Server ===
<code>
#!/bin/sh
#PBS -l select=1
#PBS -q P_016
#PBS -N sample
DIRNAME=`basename $PBS_O_WORKDIR` 
WORKDIR=/work/$USER/$PBS_JOBID 
mkdir -p $WORKDIR
cp -raf $PBS_O_WORKDIR $WORKDIR 
cd $WORKDIR/$DIRNAME

aprun python program.py

cd; if cp -raf $WORKDIR/$DIRNAME $PBS_O_WORKDIR/.. ; then rm -rf $WORKDIR; fi
</code>
\\
=== Accelerator Server ===
(Running in interactive mode)
<code>
userA@gpu2:~> qsub -I -q CA_001
qsub: waiting for job 70568.gpu1 to start
qsub: job 70568.gpu1 ready

-bash-4.2$ python
Python 3.7.8 (default, Mar 25 2021, 09:54:46) 
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

</code>
\\
You can also run python script as a job.\\
(Example)
<code>
#!/bin/sh
#PBS -l select=1
#PBS -q CA_001
#PBS -N sample
DIRNAME=`basename $PBS_O_WORKDIR`
WORKDIR=/work/$USER/$PBS_JOBID
mkdir -p $WORKDIR
cp -raf $PBS_O_WORKDIR $WORKDIR
cd $WORKDIR/$DIRNAME

python program.py

cd; if cp -raf $WORKDIR/$DIRNAME $PBS_O_WORKDIR/.. ; then rm -rf $WORKDIR; fi
</code>