Working with virtual environments.txt

When one starts to work on a project, it is generally a good idea to keep track of dependencies required by different projects.
The Python solution, is to create the so-called virtual environment. A virtual environment basically creates an isolated python 
package and dependencies list. For example, if we are working on two projects, where each project requires two different version
of the numpy package. Then, a separate virtual environment will resolve the issue. The usage of virtual environment is as follows.

1. To create a virtual environment, open anaconda-navigator, choose the environments tab and create a new environment. 
For this environment, one can specify the language such as Python or R. In addition, for Python, we can also choose the
Python version, such as 3.7.

2. While working on your project, install or update packages to the corresponding virtual environment only.

3. In case of the (likely) scenario of transferring your work to another machine or system reinstall, one can export
the environment via the following command.

(a) conda activate yourenvironmentname
(b) conda env export > environment.yml

4. In order to re-create the environment (say on another machine), just transfer the *.yml file from (3) to the target machine. 
If the anaconda navigator is present, there is a possibility to recreate (import) the environment by choosing the environments
tab and pressing import.