/shift_scheduler

Primary LanguagePython

Shift Scheduler

forthebadge made-with-python

A personal project for generating the monthly schedule for nurses at the Emergency Department in Cluj-Napoca using Google's OR-Tools CP-SAT Solver.

Shift Scheduler Log

🎯 Motivation

Creating the monthly schedule for 80+ nurses with only pen & paper when you have into account a multitude of constraints like:

  • exact number of shifts needed for each nurse
  • minimum number of nurses needed per timeslot
  • nurses with different abilities/skills - not all nurses can work on all positions in the department
  • 4-day shift plan (12/24/12/48) - employees work in shifts of 12 hours; first a day shift, followed by 24 rest hours, then a night shift , finishing with 48 rest hours. Each nurse is part of a team or cycle and should only (preferably) be assign shifts on the corresponding cycle.
  • planned rest leave days
  • fair shift allocation
  • nurse requests

is a tiresome and time-consuming task. A computer can do that job in matter of seconds if given the right instructions.

💾 Project Files Description

The project is grouped in 3 main files:

interface.py

This file contains only the class ScheduleSSManager, responsible with:

  • collecting input data for the model from Google Sheets

  • generating new spreadsheet file for the working month

  • inserting output data (generated schedule) in the new spreadsheet

  • insert the link of the newly created spreadsheet in another centralizer spreadsheet

models.py

This module is responsible for modeling and abstraction of the key concepts involved in generating the schedule:

  • Month
  • TimeSlot
  • Sector
  • Position
  • Nurse
  • Shift

The Schedule class is a utility class that only gets instantiated once and contains all data modelled with previous classes and methods and algorithms for pre-processing data that will be passed to the solver. I extensively used @cached_property from functools with the result of increasing the project execution ~10X.

solver.py

The ScheduleModel class extends cp_model.CpModel and contains methods for adding the variables and constraints to the model that will be passed to the solver.

The SolutionCollector class extends cp_model.CpSolverSolutionCallback and it's only role is to save the solution to a convenient data structure.

The file utils.py contains at the moment the class decorator class TimerLog used for conveniently logging time execution of different functions/methods in the project.

ℹ️ Usage

The project cannot be properly run without the input data that cannot be shared here, but can be used as inspiration for other projects.

🔧 Built with

This project makes use of