Programming with Python: Setup

Install Python:

You will need terminal access for this process. Contact the workshop instructor if you have no experience working in a terminal.

Test if you already have Anaconda or Miniconda installed. In your terminal type the folloing commands:

$ bash
$ which conda

If this returns nothing, please proceed to the next step. If it produces a path such as /Users/yourname/anaconda/bin/conda (yours may be different), skip the next step and go straight to step 2.

  1. Install Miniconda Python 3 by following the directions here. A video tutorial is available here. You do not need root access. We recommend Miniconda rather than Anaconda because it is a faster and more light-weight installation.

  2. Create an conda environment by running the following commands (the first may take a few minutes to execute). Replace your_env_name with something useful, say carpentries:

$ conda create --name your_env_name python -y 
$ conda activate your_env_name
$ pip install ipython numpy matplotlib astropy jupyter

Note: This should be enough to get you through the workshop but just in case, this is how you would install a new packages:

$ conda activate your_env_name
$ pip install new_package

Note: This class does not use the popular astroconda collection of packages. If you need to install that, the instructions are the first 4 yellow boxes on this page. You can use an existing astroconda environment for this class.

  1. Clean up your workspace. Check your default profile files (.cshrc, .bashrc, .bash_profile) and comment any entries that define or add to $PYTHONPATH. Start a fresh Terminal window and type echo $PYTHONPATH - you should not see a long jumble of paths to unknown corners of your hard drive. If you don’t know what this means, skip to the next one.

  2. Get yourself a nicer terminal. iTerm is really nice for OSX. For Windows, here is Git Bash.

  3. For this class we can use Nano, Emacs or VIM, but if you want a nicer text editor, download Sublime Text, Atom, BBEdit or TextWrangler. We will not cover IDEs such as PyCharm or Spyder.

Obtain lesson materials

  1. Download intro_python_data.tar.gz.
  2. Create a folder called swc-python on your Desktop.
  3. Move downloaded file into this newly created folder.
  4. Unzip the files (gunzip file.tar.gz) and untar (tar -xvf file.tar) or all in one go (tar -zxvf file.tar.gz).

You should now see a new folder called data in your swc-python directory on your Desktop.

 

If you’re using a Unix shell application, such as the Terminal or iTerm app in macOS, Console or Terminal in Linux, or Git Bash on Windows, execute the following command:

$ cd ~/Desktop/swc-python/data

On Windows, you can use its native Command Prompt program. The easiest way to start it up is by pressing Windows Logo Key+R, entering cmd, and hitting Enter. In the Command Prompt, use the following command to navigate to the data folder:

$ cd /D %userprofile%\Desktop\swc-python\data

 

Activate your Python environment

In the terminal, type the following commands:

$ bash
$ conda activate your_env_name

 

Option 1: Launch Plain Vanilla Python interpreter

To start working with Python, we need to launch a program that will interpret and execute our Python commands. To launch a “plain vanilla” Python interpreter, execute:

$ python

If you are using Git Bash on Windows, you have to call Python via winpty:

$ winpty python

 

Option 2: Start IPython interpreter

IPython is an alternative solution situated somewhere in between the plain vanilla Python interpreter and Jupyter notebooks. It provides an interactive command-line based interpreter with various convenience features and commands. You should have IPython on your system if you installed Anaconda Distribution.

To start using IPython, execute:

$ ipython

 

Option 3: Start Jupyter notebook

Jupyter notebooks provide a browser-based interface for working with Python. If you would like to use a notebook during the lesson, make sure to install Anaconda Distribution.

To start a Jupyter server, execute:

$ jupyter notebook

Then create a new notebook by clicking “New” button on the right and selecting “Python 3” from the drop-down menu: