Safari Live Training - Python By Example

Source code for the training course. Please contact me with any questions. Before beginning, be sure you know how to use git at a basic level on your computer (Windows, Mac OS, or Linux).

Contact information:
Email: njrusmc@gmail.com
Twitter: @nickrusso42518

• Download Instructions
• Usage
• Testing

Download Instructions

The easiest way to consume this code is to clone it using SSH or HTTPS.

SSH: git clone git@github.com:nickrusso42518/slt-py-example.git

or

HTTPS: git clone https://github.com/nickrusso42518/slt-py-example.git

After cloning, you should see the following file system structure:

$ tree
.
├── Makefile
├── README.md
├── complete.py
├── fundamental.py
├── inputs
│   ├── circle.yml
│   └── rectangle.json
├── requirements.txt
├── shape_pytest.py
├── shape_unittest.py
├── shapes
│   ├── __init__.py
│   ├── circle.py
│   ├── rectangle.py
│   └── shape.py
├── small
│   ├── (many files ...)
└── unittests
    ├── __init__.py
    ├── circle_test.py
    └── rectangle_test.py

Ensure you have Python 3.6 or newer installed along with pip. Ideally, you should have 3.10 to be on par with the instructor. Note that some minor features require 3.7 or 3.8, but the main programs can run on 3.6 at a minimum.

$ python --version
Python 3.10.5

Visit https://www.python.org/downloads/ to download Python.

sudo python -m ensurepip

or

sudo easy_install pip

No need to install any packages via pip; this is done during the course.

To get setup, first run make setup which will install the required Python packages and create the outputs/ directory. Failing to take this step could result in errors later in the course.

Optionally, run make to run a full suite of testing on the code to ensure everything works. After a fresh git clone there should be no errors.

Usage

There are two main programs to run, fundamentals.py and complete.py. Each program performs some computations on basic shapes, such as area and perimeter. The input data is included in the inputs/ folder and uses YAML for circle radii and JSON for rectangle lengths/widths. Outputs are written to outputs/ as JSON files.

The fundamentals.py code is a halfway point through the course used to illustrate the fundamental concepts introduced earlier in the course. It takes zero or one arguments. When no arguments are supplied, the script is interactive and asks the user whether the units are inches (in) or centimeters (cm).

$ python fundamental.py
Choose unit of measure (cm or in): in
radius 5 -> area 78.54 in sq
radius 8 -> area 201.06 in sq
radius 11 -> area 380.13 in sq
radius 5 -> perim 31.42 in
radius 8 -> perim 50.27 in
radius 11 -> perim 69.12 in
rectangle1
 8x2 -> area 16 in sq
 (8+2)x2 -> perim 20 in
rectangle2
 3x3 -> area 9 in sq
 (3+3)x2 -> perim 12 in
rectangle3
 1x6 -> area 6 in sq
 (1+6)x2 -> perim 14 in

When one argument is supplied, the script is non-interactive, as in or cm has been specified.

$ python fundamental.py cm
radius 5 -> area 78.54 cm sq
radius 8 -> area 201.06 cm sq
radius 11 -> area 380.13 cm sq
radius 5 -> perim 31.42 cm
radius 8 -> perim 50.27 cm
radius 11 -> perim 69.12 cm
rectangle1
 8x2 -> area 16 cm sq
 (8+2)x2 -> perim 20 cm
rectangle2
 3x3 -> area 9 cm sq
 (3+3)x2 -> perim 12 cm
rectangle3
 1x6 -> area 6 cm sq
 (1+6)x2 -> perim 14 cm

If the interactive or command line argument is bogus, the program keeps asking for the current input (case insensitive):

$ python fundamental.py dog
Choose unit of measure (cm or in): cat
Choose unit of measure (cm or in): monkey
Choose unit of measure (cm or in): CM
radius 5 -> area 78.54 cm sq
radius 8 -> area 201.06 cm sq
radius 11 -> area 380.13 cm sq
radius 5 -> perim 31.42 cm
radius 8 -> perim 50.27 cm
radius 11 -> perim 69.12 cm
rectangle1
 8x2 -> area 16 cm sq
 (8+2)x2 -> perim 20 cm
rectangle2
 3x3 -> area 9 cm sq
 (3+3)x2 -> perim 12 cm
rectangle3
 1x6 -> area 6 cm sq
 (1+6)x2 -> perim 14 cm

The complete.py code wraps up almost everything in this class within a simple small program. It relies on the shapes package and its component modules. The user input is similar to fundamental.py in that either in or cm must be specified with some formatting exceptions described previously. The code uses object-oriented programming, abstract classes, polymorphism, and YAML/JSON interaction for execution.

$ python complete.py cm
Type:  Rectangle
 Area:  21 cm sq
 Perim: 20 cm

Type:  Rectangle
 Area:  25 cm sq
 Perim: 20 cm

Type:  Rectangle
 Area:  6 cm sq
 Perim: 14 cm

Type:  Circle
 Area:  201.06 cm sq
 Perim: 50.27 cm

Type:  Circle
 Area:  78.54 cm sq
 Perim: 31.42 cm

Testing

A GNU Makefile with phony targets is used for testing this codebase. There are currently three steps:

• setup: Installs required Python packages in the requirements.txt file using pip. Creates outputs/ directory.
• lint: Runs YAML and Python linters. This captures any syntax or styling errors with the code.
• unit: Runs unittest and pytest unit tests for the rectangle and circle classes. This ensures the methods in each classes are operating correctly.
• run: Runs the two programs with both in and cm as inputs. The default input files should have no failures.

You can run make or make all to run all the testing in series when doing manual regression testing from the shell. As mentioned earlier in the README, this is a good idea after first cloning the repository.