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A small python package to visualise recursive function on Python. It draws recursion tree

Project description

Recursion Visualiser

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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.


1. Installing graphviz


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/'  


  • 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

  1. Download Docker file from repo
curl --output Dockerfile
  1. Download docker-compose.yml
curl --output docker-compose.yml
  1. Start docker container
CURRENT_UID=$(id -u):$(id -g) docker-compose up
  1. Run any python scripts and run using
docker-compose exec vs python


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)  


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
    # Save recursion tree to a file
    vs.make_animation("fibonacci.gif", delay=2)

if __name__ == "__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: enter image description here

enter image description here


Find other examples here and read more about recursion-visualiser here


  • Minimal working version
  • Upload package to pypi
  • Support animation
  • Add node styles
  • Support aliasing for function name
  • Show repeated states
  • Support node_color, backgroundcolor etc
  • Refactor
  • Handle base cases
  • Make more beautiful trees

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