Recursion Visualiser

Recursion visualiser is a python tool that visualizes recursion tree with animation and draws recursion tree for recursive function. It works with almost any type of recursive function. Just add the recursion-visualiser decorator to your function and let it do the rest of the work.

Installation

1. Installing graphviz

Windows

The only dependency for recursion visualiser is Graphviz

Download graphviz binary
Add graphviz bin to path manually or by adding the following line on your script. Change the installation directory according to your installation path

# Set it to bin folder of graphviz  
os.environ["PATH"] += os.pathsep +  'C:/Program Files (x86)/Graphviz2.38/bin/'

Ubuntu

Install graphviz

 sudo apt install graphviz

The instructions to install graphviz for other operating system is available here

2. Installing recursion-visualiser

The easiest way to install recursion-visualiser package is from pypi

pip install recursion-visualiser

An alternative way is to clone the repository and install all the requirements.

pip install -r requirements.txt

Alternative Installation using Docker

If you have docker and docker-compose installed then you can install recursion-tree-visualiser using Docker and docker-compose.yml file

Download Docker file from repo

curl https://raw.githubusercontent.com/Bishalsarang/Recursion-Tree-Visualizer/master/Dockerfile --output Dockerfile

Download docker-compose.yml

curl https://raw.githubusercontent.com/Bishalsarang/Recursion-Tree-Visualizer/master/docker-compose.yml --output docker-compose.yml

Start docker container

CURRENT_UID=$(id -u):$(id -g) docker-compose up

Run any python scripts and run using

docker-compose exec vs python fibonacci.py

Usage

The preferred way to import the decorator class from the package is as:

from visualiser.visualiser import Visualiser as vs

1. Fibonacci

Let's draw the recursion tree for fibonacci number.
Here is how the simple code looks like

def fib(n):  
    if n <= 1: 
        return n 
    return fib(n - 1) + fib(n - 2)  

print(fib(6))

Now we want to draw the recursion tree for this function. It is as simple as adding a decorator

# Author: Bishal Sarang

# Import Visualiser class from module visualiser
from visualiser.visualiser import Visualiser as vs

# Add decorator
# Decorator accepts optional arguments: ignore_args , show_argument_name, show_return_value and node_properties_kwargs
@vs(node_properties_kwargs={"shape":"record", "color":"#f57542", "style":"filled", "fillcolor":"grey"})
def fib(n):
    if n <= 1:
        return n
    return fib(n=n - 1) + fib(n=n - 2)


def main():
    # Call function
    print(fib(n=6))
    # Save recursion tree to a file
    vs.make_animation("fibonacci.gif", delay=2)


if __name__ == "__main__":
    main()

Here are the changes required:

Add decorator Visualiser which accepts optional arguments ignore_args, show_argument_name and 'show_return_value'
Change every function calls to pass as keyword arguments.
Make_animation

The output image are saved as "fibonacci.gif" and "fibonacci.png"

Here is how the recursion tree looks like:
Animation: