ALBP file reader

[micheleurbani]

ALBP file reader

Accessing ALBP information directly to guide the search process is necessary because retrieving them from the ecole.scip.Model is pretty inconvenient. The assumption of having all the problem information available is largely accepted in the literature and is a basic assumption in all papers.

Inherit from FileGenerator class

The ecole.instance.FileGenerator iterates over a folder and its subfolders to find .mps and .lp files.
The class is written in C++ and could be used to read row ALBP files, retrieve the information, and create a scip.Model which stores ALBP information directly.

A list of possible issues is the following:

• Each problem presents a different dataset structure and a switch statement would be required to differentiate the procedure for all of them.

Python objects and .lp model

pyscipopt.Model objects are not serializable, therefore it is impossible to rely on these only.

Problem data are stored as plain Python dictionaries using pickle. The instance generator iterates over .lp problem files, reads the model, initializes a pyscipopt.Model, reads model data, and appends this to the data attribute of the pyscipopt.Model object.

Randomization of results

The ecole.RandomGenerator class controls the fetching process.