Python instllation and set up
=============================

This page describes how to **install** and **set up Python** on the computer.

Download Anaconda
-----------------

Anaconda is a free, easy-to-install package and environment manager, which is "a distribution of the Python and R programming languages for scientific computing, that aims to simplify package management and deployment." by Wikipedia. 

Follow `the instructions of the Anaconda homepage <https://docs.anaconda.com/anaconda/install/index.html>`_ to download and install Anaconda.

Create virtual environments
---------------------------

If you use Python framework and library without a virtual environment, these libraries will be added in one place. As a result, the libraries may interface with each other and suddently nor work. 
To avoid this issue and continue to use your Python programming, I recommend to create a virtual environment isolated for Python projects. 
This means that each project has its own libraries and frameworks, which makes it easier to manage Python enviroments.

How to create virtual environments 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

(This information is copied from `PyCLIM webpage <https://climate.usu.edu/people/yoshi/pyclm101/setup.html#installaion>`_.)

Update conda

.. literalinclude:: SRC/setup.txt
   :lines: 1

Create a virtual environment for each project. 
Enter your favorite project name in "env_weclim" of the command below.

.. literalinclude:: SRC/setup.txt
   :lines: 2

Install packages in the created virtural enviroment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Numpy and Xarry are libraries for the multi-dimensional analysis. PANDAS, a popular data analysis tool, is also installed automatically when you install Xarray.

.. literalinclude:: SRC/setup.txt
   :lines: 4

Matplotlib and Cartopy are libraries for xy plots and geosphatial mapping.

.. literalinclude:: SRC/setup.txt
   :lines: 5

Dask is a library for effectively computing in paralle.

.. literalinclude:: SRC/setup.txt
   :lines: 6

If you want to analyze a one-dimensinal dataset (such as time-series data), the above package will suffice. 
When performing  multi-dimensional analysis using NetCDF format datasets such as climate model output, GeoCAT is a useful tool for data analysis and visualization.

.. literalinclude:: SRC/setup.txt
   :lines: 8 

'eof' is a library for empirical orthogonal function (EOF) analysis to identify the main variations of variables.

'geocat-datafiles' is a libary for calculating ocean stream function.

.. literalinclude:: SRC/setup.txt
   :lines: 10

Activate the virtual environment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Finally, activate the virtural environment named "env_weclim".

.. literalinclude:: SRC/setup.txt
   :lines: 12

This command should be run every time you start your computer and start a project.

Other tips
~~~~~~~~~~

Deactivate the virtual environment

.. literalinclude:: SRC/setup.txt
   :lines: 14

Remove the virtual enviroment

.. literalinclude:: SRC/setup.txt
   :lines: 15

Check if Python works

Run a python script. 
Download and save this file: :download:`test.py <SRC/test.py>` and run the following python command.

.. literalinclude:: SRC/setup.txt
   :lines: 17

If 'Hello, World!' is displayed, Python is working.