Solving Linear Programming Problems in Python

(The naive way)

1. Setup the Environment

This assumes that you already have python installed.
The Program was tested using Python 3.9.1 installed using Anaconda Distrubution.

If you are using Anaconda Distrubution

Create the environment and install the requirements

conda create --name lpp_env --file requirements.txt

Activate the Enviroment

conda activate lpp_env

If you are using python virtual environment

Basically, please make sure that all the dependencies are installed before running the main.py file.

Create a Virtualenv

python3 -m venv env_name

Activate the env

.\env_name\Scripts\activate

Install the Dependencies

pip install -r requirements.txt

Note: If pip install fails for some reason (e.g. Due to not having proper build tools to install numpy, matplotlib, etc), you can also run:

easy_install numpy scipy matplotlib tabulate

The virtual environment has the script easy_install.exe in ./env_name/Scripts which can be used to install the required packages packages

2. To run the program run the command in the terminal

python main.py -i input_filename

eg:

python main.py -i input.txt

When a plot is displayed, Please close the plot window to proceed the next problem.

Changing the inputs to the program

All the input problems are stored in a text file which we pass to the main.py when we run the program.

Rules for the input text file

A line beginning with a # is treated as a comment and will be ignored.
Leave a single blank line between two LPPs.
The variables can be anything. eg: x_1 and x_2, x1 and x2, a and b, or x and y, etc.
Please leave no space between the coefficient and the variable. Anything after a number will be treated as a variable.
eg:
5x_1: coefficient 5 , variable x_1
5x1: coefficient 5 , variable x1
Please use the signs >=, <= or = for the constraints.
Do not use unicode symbols like, ≥ or ≤, because the program won't parse these symbols.

Example Format of LPP:

  Maximize: z = 5x_1 + 4x_2
  Subject to:
      6x_1 + 4x_2 <= 24
      x_1 + 2x_2 <= 6
      -x_1 + x_2 <= 1
      x_2 <= 2
      x_1 >= 0
      x_2 >= 0

Note: The program can also handle LPPs with three or more variables. A sample input file input.txt is included with a three variable LPP at the end.

reuelrds / NaiveLPPSolver