What?

This repository contains Python skeleton for programming assignments of Coursera course "Probabilistic Graphical Models" by Daphne Koller.

All the assignments from part A, B and C have been ported.

The course assignments are written in MATLAB/OCTAVE. I personally find this language harder in modern times and feel that newcomers generally would be more familiar with Python than MATLAB.

Also, the course assignments provide a lot of boilerplate code which also contains a lot of details. I felt that implementing the assignments+boilerplate in Python would be a better way to master the course material.

How?

Download the original zip and extract it somewhere. Copy all *.mat files from that directory into data directory inside respective assignment here.

All functions that you will have to implement are in solution.py. Once you are finished with one function implementation, you can check your implementation locally in check.ipynb. This notebook does the work of reading .mat file and converting it into appropriate structures.

Once you are satisfied with your solution, you can submit your solution by running submit.py script. The script will ask you for your email address and token.

Before you start second assignment,

Please go through my implementation of factor. This is the most important/common class that you will work with.

NOTE: Please do not view that file for assignment 1. As it might spoil couple of answers for this assignment. This is same in original MATLAB code as well. Answers to some of the questions are implemented in later assignments, so you do not have to keep reinventing the wheel over and over again.

Factor is basically a lookup table (a dictionary) made of discrete variables. Each variable has some cardinality. Say you want to create a factor over two binary variables. Use Factor([0, 1], [2, 2]). The first argument is a list of variable names. Second argument is cardinality of each variable in first argument.

• Also note that I've used 0 based indexing unlike original MATLAB code, so variable 1 can take either value 0 or 1.

Note:

• Although I've tested the assignments (i.e. almost in all cases I got 100/100.), there could be hidden bugs which might mark your solution wrong even though your solution is correct. If you feel that your solution is correct but it is marked wrong, please debug first in the check.ipynb and see if expected output matches with your output, and then raise an issue. I'll look into it.

Acknowledgements

• The Python grader is derived from Gerges Dib's code, which itself is derived from Marcel Stampfer's code.