Detect cars going over the limit by time differences in plate detectors.

Solves a fun StackOverflow problem in Python.

• Python 3.9 or later (use of typing hints)
• Poetry package manager, to install development dependencies and generate virtual environment. No actual runtime dependency.

Install the module first:

make install
# or
poetry install

Then inside the virtual environment, launch the script:

# Run single command inside virtualenv
poetry run speeders -f input_2.txt

# or
# Load the virtualenv first
poetry shell
# Then launch the script, staying in virtualenv
speeders -f input_2.txt

Sample output:

The following 4 cars went over the speed limit:
QW-23-56 - 72 km/h
02-RV-WE - 55 km/h
CF-QW-46 - 60 km/h
03-LC-TF - 65 km/h

Use this package as you would any python module:

# Get a virtualenv going first, such as via poetry
poetry shell
python3
>>> from plates import match

See the original problem on Stack Overflow.

I have to print a list of license plate numbers of all cars that went over the speed limit, as well as the average speed of each of those cars.

The first line contains the maximum speed (in km/h) for the road that the detectors are placed on. All other lines start with the number of the detector that was passed (1 or 2), followed by the time on which the car passed the detector, and then followed by the license plate number of that car.

Example input:

50
1 09:00:00 OZ-15-ZU
2 09:00:04 WS-LP-74
1 09:00:07 97-YC-51
1 09:00:10 NV-71-PU
2 09:00:21 OZ-15-ZU
[...]
2 09:04:58 CN-70-OT

Example output:

The following cars went over the speed limit:
GH-23-NN - 68 km/h
NV-71-PU - 56 km/h
CN-70-OT - 70 km/h
18-IP-VU - 59 km/h

Input:

50
1 12:00:33 QW-23-56
1 12:01:39 GF-PY-26
2 12:00:43 QW-23-56
1 12:00:46 02-RV-WE
2 12:00:59 02-RV-WE
2 12:01:56 GF-PY-26
1 12:01:15 CF-QW-46
2 12:02:13 WM-20-PF
2 12:01:27 CF-QW-46
1 12:01:28 03-LC-TF
2 12:01:39 03-LC-TF
1 12:01:56 WM-20-PF

Output:

The following cars went over the speed limit:
QW-23-56 - 72 km/h
02-RV-WE - 55 km/h
CF-QW-46 - 60 km/h
03-LC-TF - 65 km/h

Note from implementor: the distance between detector plates is NOT stipulated, which is required to capture speed as distance over time. Sample implementation shows this to be 200 meters.

This repository uses Python 3.9 or above, using Poetry as package manager to define a Python package inside src/plates/.

poetry will create virtual environments if needed, fetch dependencies, and install them for development.

This codebase uses pre-commit to run linting tools like flake8, formatters like black, and type checking via mypy.

Use pre-commit install to install git pre-commit hooks to force running these checks before any code can be committed, use make lint to run these manually.

Testing is provided by pytest separately in make test.

Installation of poetry and pre-commit is recommended via pipx.

For ease of development, a Makefile is provided, use it like this:

make  # equivalent to "make all" = install lint docs test build
# run only specific tasks:
make install
make lint
make test
# Combine tasks:
make install test

This project is released under GPLv3. See COPYING file for GPLv3 license details.