treelib/docs/source/index.rst

.. treelib documentation master file, created by
   sphinx-quickstart on Thu Dec 20 16:30:18 2018.
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Welcome to treelib's documentation!
***********************************

.. toctree::
   :maxdepth: 2
   :caption: Contents:

Introduction
============

`Tree <http://en.wikipedia.org/wiki/Tree_%28data_structure%29>`_ is an
important data structure in computer science. Examples are shown in ML algorithm designs such as random forest tree and software engineering such as file system index. `treelib <https://github.com/caesar0301/pyTree>`_ is created to provide an efficient implementation of tree data structure in Python.

The main features of `treelib` includes:
   * Efficient operation of node searching, O(1).
   * Support common tree operations like **traversing**, **insertion**, **deletion**, **node moving**, **shallow/deep copying**, **subtree cutting** etc.
   * Support user-defined data payload to accelerate your model construction.
   * Pretty tree showing and text/json dump for pretty show and offline analysis.
   * Compatible with Python 2 and 3.

Installation
============

The rapidest way to install treelib is using the package management tools like
``easy_install`` or ``pip`` with command

	.. code-block:: sh

		$ sudo easy_install -U treelib

or the setup script

	.. code-block:: sh

		$ sudo python setup.py install

**Note**: With the package management tools, the hosted version may be falling
behind current development branch on `Github
<https://github.com/caesar0301/pyTree>`_. If you encounter some problems, try
the freshest version on Github or open `issues
<https://github.com/caesar0301/pyTree/issues>`_ to let me know your problem.

Examples
========

Basic Usage
-------------

.. code-block:: sh

    >>> from treelib import Node, Tree
    >>> tree = Tree()
    >>> tree.create_node("Harry", "harry")  # root node
    >>> tree.create_node("Jane", "jane", parent="harry")
    >>> tree.create_node("Bill", "bill", parent="harry")
    >>> tree.create_node("Diane", "diane", parent="jane")
    >>> tree.create_node("Mary", "mary", parent="diane")
    >>> tree.create_node("Mark", "mark", parent="jane")
    >>> tree.show()
    Harry
    ├── Bill
    └── Jane
        ├── Diane
        │   └── Mary
        └── Mark


API Examples
--------------

**Example 1**: Expand a tree with specific mode (Tree.DEPTH [default],
Tree.WIDTH, Tree.ZIGZAG).

.. code-block:: sh

    >>> print(','.join([tree[node].tag for node in \
                tree.expand_tree(mode=Tree.DEPTH)]))
    Harry,Bill,Jane,Diane,Mary,Mark

**Example 2**: Expand tree with custom filter.

.. code-block:: sh

    >>> print(','.join([tree[node].tag for node in \
                tree.expand_tree(filter = lambda x: \
                x.identifier != 'diane')]))
    Harry,Bill,Jane,Mark

**Example 3**: Get a subtree with the root of 'diane'.

.. code-block:: sh

    >>> sub_t = tree.subtree('diane')
    >>> sub_t.show()
    Diane
    └── Mary

**Example 4**: Paste a new tree to the original one.

.. code-block:: sh

    >>> new_tree = Tree()
    >>> new_tree.create_node("n1", 1)  # root node
    >>> new_tree.create_node("n2", 2, parent=1)
    >>> new_tree.create_node("n3", 3, parent=1)
    >>> tree.paste('bill', new_tree)
    >>> tree.show()
    Harry
    ├── Bill
    │   └── n1
    │       ├── n2
    │       └── n3
    └── Jane
        ├── Diane
        │   └── Mary
        └── Mark

**Example 5**: Remove the existing node from the tree

.. code-block:: sh

    >>> tree.remove_node(1)
    >>> tree.show()
    Harry
    ├── Bill
    └── Jane
        ├── Diane
        │   └── Mary
        └── Mark

**Example 6**: Move a node to another parent.

.. code-block:: sh

    >>> tree.move_node('mary', 'harry')
    >>> tree.show()
    Harry
    ├── Bill
    ├── Jane
    │   ├── Diane
    │   └── Mark
    └── Mary

**Example 7**: Get the height of the tree.

.. code-block:: sh

    >>> tree.depth()
    2

**Example 8**: Get the level of a node.

.. code-block:: sh

    >>> node = tree.get_node("bill")
    >>> tree.depth(node)
    1

**Example 9**: Print or dump tree structure. For example, the same tree in
 basic example can be printed with 'ascii-em':

.. code-block:: sh

    >>> tree.show(line_type="ascii-em")
    Harry
    ╠══ Bill
    ╠══ Jane
    ║   ╠══ Diane
    ║   ╚══ Mark
    ╚══ Mary

In the JSON form, to_json() takes optional parameter with_data to trigger if
the data field is appended into JSON string. For example,

.. code-block:: sh

    >>> print(tree.to_json(with_data=True))
    {"Harry": {"data": null, "children": [{"Bill": {"data": null}}, {"Jane": {"data": null, "children": [{"Diane": {"data": null}}, {"Mark": {"data": null}}]}}, {"Mary": {"data": null}}]}}

**Example 10**: Save tree into file
  The function save2file require a filename.
  The file is opened to write using mode 'ab'.

.. code-block:: sh

    >>> tree.save2file('tree.txt')


Advanced Usage
----------------

Sometimes, you need trees to store your own data. The newest version of
:mod:`treelib` supports ``.data`` variable to store whatever you want. For
example, to define a flower tree with your own data:

.. code-block:: sh

    >>> class Flower(object): \
            def __init__(self, color): \
                self.color = color

You can create a flower tree now:

.. code-block:: sh

    >>> ftree = Tree()
    >>> ftree.create_node("Root", "root", data=Flower("black"))
    >>> ftree.create_node("F1", "f1", parent='root', data=Flower("white"))
    >>> ftree.create_node("F2", "f2", parent='root', data=Flower("red"))

Printing the colors of the tree:

.. code-block:: sh

    >>> ftree.show(data_property="color")
        black
        ├── white
        └── red

**Notes:** Before version 1.2.5, you may need to inherit and modify the behaviors of tree. Both are supported since then. For flower example,

.. code-block:: sh

    >>> class FlowerNode(treelib.Node): \
            def __init__(self, color): \
                self.color = color
    >>> # create a new node
    >>> fnode = FlowerNode("white")


Indices and tables
==================

* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`