coeden 0.2.3

Coeden is a idiomatic library to work with trees in python

Coeden for python

Coeden is a library to make work with tree data structures ergonimic and ideomatic in python.

Disclaimer

This library is in an early alpha stage, expect major changes in the API in subsequent versions.

Getting started

Requirements

Python >= 3.10.x

Install

You can install it with pip:

python3 -m pip install coeden

Documentation

Create a tree

In coeden there is no tree object, the trees are made of nodes and from every node you can create new leafs (nodes without childs).

Let's create a simple tree with 3 levels of depth:

from coeden import node

color_tree = Node("colors")

and this node can grow new leafs

color_tree["colors"].new_leaf("red")
color_tree["colors"].new_leaf("blue")
color_tree["colors"].new_leaf("green")

then blue can grow a couple of leafs or typing the whole chain

color_tree["colors"]["blue"].new_leaf("marine")
color_tree["colors"]["blue"].new_leaf("celeste")

also, the red node can be stored in a variable and grow some leafs from it

red = color_tree["colors]["red"]
red.new_leaf["dark"]
red.new_leaf["velvet"]

The current tree can be printed like this

color_tree.print_tree()

# Output
colors
  red
    dark
    velvet
  blue
    marine
    celeste
  green

but as all nodes are the starting point of their own tree blue can print its own tree, that happens to be a subtree of colors because blue belong to colors

blue.print_tree()

# Output
blue
  marine
  celeste

Traversing the tree

Trees are traversed using the index operator []. Using the brackets you can traverse the previous tree from the root to the velvet node for example

if color_tree["red"]["velvet"] != None:
    ...    

this is kind of a nested dictionary (and they are internaly nested dictionaries indeed) but it hides some interesting features that normal dicts do not.

Traverse inexistent nodes

Imagine you want to check the existance of "dark gray" in the tree with dictionaries you have to do something like:

if color_tree["gray"] != None and color_tree["gray"]["dark"] != None:
    ...

or at least wrap it in a try/except. But coeden allows to make free test for existance

if color_tree["gray"]["dark"] != None:
    print("Nice color!")
else:
    print("Nah, not a real color")

# Output
Nah, not a real color 

or even better you can create al the inexistent nodes in one call with

color_tree["gray"]["dark"].create_all()
color_tree.print_tree()

# Output
colors
  red
    dark
    velvet
  blue
    marine
    celeste
  green
  gray
    dark

Wildcards

Wilcards allow to consider every node of a level, for instance, we can search for marine node without knowing it is blue.

marine = color_tree["__*__"]["marine"]  # Marine is an iterable set of nodes

but wildcards return sets of nodes and not nodes so there are two options, if you know that there is going to be only one node you can use the special key "__?__" that converts the set to a node again if its length is exactly one. If there are more the sets can be iterated in a loop.

marine = color_tree["__*__"]["marine"]["__?__"]  # Now it is the node 
print("marine parent: " + marine.parent.key)

for node in color_tree["__*__"]["dark"]:
   print("dark parent: " + node.key)

# Output
marine parent: blue
dark parent: red
dark parent: gray