CSPP instance

This Python script (<code>instance_generator.py</code>) is a tool designed to <b>programmatically generate synthetic instance data for container stowage and logistics problems.</b>Its primary function is to create structured datasets that simulate container terminal operations, which can then be used for developing, testing, and benchmarking optimization algorithms (e.g., for yard stacking strategies, vessel stowage planning).Key features and workflow include:<b>Parameterized Generation</b>: The script allows users to customize the generated data by specifying parameters such as:The total number of containers to create.The number of distinct attribute groups (simulating different container types, destinations, etc.).The configuration of the yard (number of areas, bay structure, rows, and levels).The configuration of the vessel (bay structure, rows, and tiers).<b>Data Initialization</b>:It internally creates a DataFrame to hold the instance data.Unique container numbers (<code>CNTR_NO</code>) are generated for each container.Containers are randomly assigned to different attribute groups (<code>attr_group_no</code>).<b>Yard Location Assignment</b>:The script systematically assigns each container a specific location in the simulated yard, including <code>area_no</code>, <code>area_bay</code>, <code>area_row</code>, and <code>area_level</code>.It also generates a standardized yard location code (<code>VPC_VLOCATION</code>) for each container.<b>Vessel Location Assignment</b>:Containers are assigned target locations on a simulated vessel (<code>ship_bay</code>, <code>ship_row</code>, <code>ship_tie</code>).This assignment is typically based on the container's attribute group, ensuring that similar containers are often grouped together on the vessel.It also sets related flags like <code>is_in_cabin</code> (indicating if the container is in the hold or on deck).<b>Direct Execution</b>: The script is set up to run directly. When executed, it uses a predefined set of parameters (which can be easily modified within the script) to generate an instance and can save this data to a CSV file (e.g., <code>generated_stowage_instance_direct.csv</code>).