Employee Shift Scheduling Tool

Overview

This Python-based scheduling tool assigns employees to shifts while satisfying various hard and soft constraints, ensuring optimal shift coverage and fairness in employee allocation. The tool is powered by Google OR-Tools (CP-SAT Solver) and is designed to handle complex scheduling requirements efficiently.

The generated schedule is exported to a CSV with intuitive tables for easy analysis and usage.

Features

1. Constraint Satisfaction

The tool enforces the following hard constraints:

• Coverage Requirement: Each time slot must have exactly 2 employees.
• Shift Lengths: Employees are assigned single shifts of 6–8 hours (or shorter if daily availability is less than 6 hours).
• Weekly Hour Limits: Employees cannot exceed their predefined weekly working hours (40 hours per week by default for full time employees. However, managers have the authority to adjust this limit as needed).
• Forbidden Pairs: Prevents specific pairs of employees from being assigned to the same shift.
• Shift Continuity: Day-based single-shift patterns are strictly enforced.

2. Soft Objectives

The tool minimizes deviations from employees' preferences, including:

• Assigning employees their desired number of shifts whenever possible.
• Ensuring employees requesting exactly 1 or 2 shifts are strictly matched.

3. CSV Export

The resulting schedule is exported in a user-friendly format:

1. Time vs. Day Grid: Displays shifts in a grid format, preserving occupant continuity by listing each employee’s name at the top of their contiguous block.
2. Summary Table: Includes details for each employee:
   • Weekly hours
   • Desired shift count
   • Actual shift count

Technologies Used

• Python
• Google OR-Tools (CP-SAT Solver) for constraint satisfaction modeling
• pandas for data manipulation and CSV export

How It Works

1. Define employees, availability, and constraints in an input configuration file (e.g., JSON or CSV).
2. The tool constructs a constraint satisfaction model with the following logic:
   • Coverage requirements per slot (AddEquality).
   • Single-shift patterns and continuity (AddAllowedAssignments).
   • Weekly limits and forbidden pairs.
3. The model is solved using the CP-SAT solver, optimizing for fairness and minimizing deviations from employee preferences.
4. Export the schedule to a CSV file containing:
   • A time vs. day grid for shift visualization.
   • A summary table for performance review and adjustments.

Getting Started

Prerequisites

• Python 3.8+
• Google OR-Tools
• pandas

Installation

1. Clone the repository:

   git clone https://github.com/ShinLiX/shift_schedule.git
   cd shift_schedule

2. Install dependencies

   pip install -r requirements.txt

3. Run the script

   python scheduler.py