lolviz

A simple Python data-structure visualization tool for Lists Of Lists, lists, dictionaries, and linked lists; primarily for use in Jupyter notebooks / presentations. It seems that I'm always trying to describe how data is laid out in memory to students. There are really great data structure visualization tools but I wanted something I could use directly via Python in Jupyter notebooks. The look and idea was inspired by the awesome Python tutor.

There are currently five functions of interest that return graphviz.files.Source objects:

• dictviz(): A dictionary visualization
  
• listviz(): Horizontal list visualization
  
• lolviz(): List of lists visualization with the first list vertical and the nested lists horizontal.
  
• llistviz(): Linked list visualization with horizontal orientation
  
• treeviz(): Binary trees showing top-down
  

Installation

First you need graphviz. On a mac it's easy:

$ brew install graphviz

$ pip install lolviz

Usage

From within generic Python, you can get a window to pop up using the render() method:

from lolviz import *
g = listviz(['hi','mom',{3,4},{"parrt":"user"}])
g.render(view=True) # render graphviz.files.Source object

From within Jupyter notebooks you can avoid the render() call because Jupyter knows how to display graphviz.files.Source objects:

You can look at a list of tuples as a list of list too:

Here's how to describe a hashtable with 3 elements in 2 different buckets:

If you want the graphviz/dot source, use source field of returned graphviz.files.Source object.

For 1.1, I added linked lists. Figuring out that layout was annoying. You're welcome. ;)

Here's an example of specifying lambda functions to extract values from nodes:

Here's an example for binary trees:

class Tree:
    def __init__(self, value, left=None, right=None):
        self.value = value
        self.left = left
        self.right = right

root = Tree('parrt',
            Tree('mary',
                 Tree('jim',
                      Tree('srinivasan'),
                      Tree('april'))),
            Tree('xue',None,Tree('mike')))
treeviz(root)

And another:

root = ('parrt',('mary',('srinivasan',None,None),('april',None,None)),None)
treeviz(root, value=lambda t:t[0], left=lambda t:t[1], right=lambda t:t[2])