Let us assume that you want to install some research code to either use it or test the results. It might use an older version of a particular package that you have already installed.
One option is to create a virtual environment using
Virtualenv is a Python package to create isolated Python environments and can be installed through pip, the Python package manager: pip install virtualenv or pip3 install virtualenv (if using Python 3).
This is a simple way of creating a Python environment. Replace the word ENVIRONMENT with the name that you want to call the environment. The -p option will link to your machine’s python3 executable.
virtualenv -p python3 ENVIRONMENT
When it is created, then start the environment using
source ENVIRONMENT/bin/activate
This starts the isolated environment so that you can install the required pacakges and develop it without affecting other pieces of code.
Once you have developed the code, you can save the package requirements using pip
(ENVIRONMENT) pip freeze > requirements.txt
This will save the packages used and the current version into a text file. The file should be added to your repository to help others install it.
If you have downloaded or cloned a repository and started a virtual environment, then you can start the environment and install the requirements using:
(ENVIRONMENT) pip install -r requirements.txt
This will install the packages and versions. You can, manually, remove the package versions from the requirements, but this leaves you open to having different versions of packages on different machines.
It is a choice. The pinning of packages to certain versions can cause issues when Python is upgraded and a version is no longer supported. However it does mean that the same version is in use for the project and could be upgraded at some point.
Binder allows you to run Jupyter notebooks in an executable environment to support reproducibility. It uses Jupyter and, for Python, the requirements.txt file from pip to install the notebook. The MyBinder is an open resource that allows you to build from Github.
The service provides a shareable link and button that can launch your notebook (but it can take a few minutes).
This website uses a very simple notebook but MyBinder is well documented and very helpful.